The Grasses – Some Notes on Identification by Prof Ian Trueman, April 2018

The Grasses – Some Notes on Identification

by Prof Ian Trueman April 2018 Edited by Mags Cousins

Contents Part 1 – Introduction and the Bents (genus Agrostis) Newsletter No. 24, Spring 2012 Part 2 – The spike inflorescence Newsletter No. 25, Autumn 2012 Part 3 – Spike-like Panicles Newsletter No. 27, Autumn 2013 Part 4.1 – The clearly-branched Panicles, Newsletter No. 29, Autumn 2014 Part 4.2 – the fourth and final group of the clearly-branched Panicles, Newsletter No. 32, Spring 2016

This booklet is a reproduction of a series of articles written by Prof Ian Trueman for the Shropshire Botanical Society newsletter. The descriptions, notes and illustrations are to aid in the confident identification of this important group of plants.

Part 1 – Introduction and the Bents (genus Agrostis) Introduction “All flesh is grass, and all the goodliness thereof is as the flower of the field” (Isiah 40:6). Grass becomes the flesh of the herbivores, which flourish partly because the grasses have evolved to withstand grazing. The remarkable two-part grass leaf has a basal tubular or rolled sheath and (with the collar-like ligule where the two join), a terminal blade, which will regrow rapidly from its base if it is grazed off. The vegetative grass shoot consists of successively-produced leaf sheaths, each inside the previous one, with the shoot’s growing point inside at the base and with the true stem remaining short. If the whole shoot is grazed off, the grass continues to grow without having to regenerate its growing point from a dormant bud as in most plants. So grasslands are more productive and less easily damaged by grazing than most other types of vegetation and can support more grazing stock.

Also world civilizations developed largely by cultivating cereals, which are all annual grasses with adaptations which allow reliable long-term cultivation under conditions of seasonal rainfall over wide areas of the planet.

The grass inflorescence develops at the growing point protected at ground level and only at a late stage of development does the stem elongate. The tiny wind-pollinated flower (or floret) is protected from desiccation by being encased in a complex set of wrappings derived from the simplification of the structures of an original group of flowers. The innermost pair of wrappings, the lemma and palea separate briefly to expose stamens and stigmas for pollination and close again for the protection and often the dispersal of the developing grain, which itself is a simplified one-seeded fruit.

Thus, as bread and meat, all flesh is grass!

Genus Agrostis, the Bents Our bents are mostly smallish hairless perennial grasses. The leaf blades are broadest near the base and therefore typically appear narrowly triangular. They are usually flat and ±10-veined without a marked raised midrib beneath.

Some bents have rhizomes - elongated underground stems with reduced, scale-like leaves on which the condensed stems described above are borne at nodes (regular intervals on the stem).

In others the above-ground, leafy stems elongate while the shoot is still vegetative to form trailing stolons which may root at the nodes. The shape of the membranous ligule differs from species to species.

Agrostis species flower later than most grasses, generally from late June. The inflorescence is a panicle, i.e. with spreading branches, which get shorter above to give a distinctive pyramidal outline when fully open. However as is always with the case with grasses the inflorescence starts narrow, with the branches tightly clustered and only later does it open. In some species the panicle then stays open permanently, in others it closes again in fruit.

At the end of the finest branches are the reproductive units which in grasses are not the florets but clusters of florets called spikelets, delimited by two extra sterile lemma-like scales at the base called glumes. In most grasses there is a pair of flowers or a double row of florets in

each spikelet, but Bents have the simplest possible spikelet imaginable - a single flower is enveloped in two glumes. You may have to separate these glumes to see the translucent lemma and palea when identifying Bents.

In some the palea is at least half the length Agrostis capillaris spikelet x15 of the lemma, in others it is extremely short. In some species the lemma may bear lemma stamens palea a fine, bent bristle-like awn from the back, but be aware that the awns can often fail to develop and development may vary from spikelet to spikelet in one inflorescence.

glume

species capillaris stolonifera gigantea vinealis canina

glume

habit rhizomes stolons rhizomes rhizomes stolons

Culm leaf ligule length 0.5-1.5 2.0-6.5 2.0-7.5 1.0-4.0 1.5-4.5

This meagre group of characters is practically all we have to distinguish between the species. Hybridisation is quite common which doesn’t help, although all the hybrids are very sterile. Here is a basic comparative table which should deal with most specimens. Be ready to dig up the rhizomes!

Culm leaf ligule shape b>l ± truncate b<l ± rounded b≤l ± rounded b<l ± pointed b<l ± pointed

Panicles close later no strongly no usually somewhat

Palea minute no no no yes yes

awns rare rare very rare ±basal or 0 ±basal or 0

Agrostis capillaris, Common Bent, is ubiquitous in unimproved grassland and lawns and recognisable by its very short, blunt ligule and beautiful panicle in which the branches and THEIR branchlets all spread widely and evenly into fruit. It is usually quite small but can vary widely in size. Agrostis stolonifera, Creeping Bent, is equally ubiquitous and even more polymorphic but is especially common in the wet, or sending its long stolons into bare patches of ground. Its ligules are also fairly blunt, but longer than wide and the inflorescence becomes very narrow in fruit. Be aware that A. capillaris can become stoloniferous late in the season. Agrostis gigantea, Black Bent, probably very common on disturbed and cultivated ground, is almost always quite large (culm leaf 3mm wide plus) and has even more prominent rhizomes than capillaris but a long ligule like stolonifera. The spikelets are more clustered at branch tips than in capillaris but as in that species the inflorescence closes little in fruit.

Two less common species are generally recognised by their consistently small size, weaklychannelled leaf bades, long, pointed ligules and awned florets. Actually the key difference is the vestigial palea, less than 1/3 the length of the lemma (1/2 the length of the lemma or more in the previous three species). Awns and ligules are less reliable! Agrostis vinealis, Brown Bent starts to flower mid-June in dry heathland and acid grassland, often alongside capillaris.

Agrostis canina, Velvet Bent, grows in fairly base- and nutrient-poor wetland habitats. Its stolons root and branch widely at the nodes to give a very characteristic low, loose mat which has led to it being used as a lawn grass. It seems not to bother flowering in some habitats.

Not, I think, known from vc. 40 are the following species. A. castellana, the Highland Bent, possibly in seed mixtures, which would key out as a small, almost tufted A. gigantea, but the lemmas of the terminal florets on a branch are covered thinly in fine hairs. There are a few very rare alien annual Bents also with hairy lemmas. The one bristle-leaved Bent: Agrostis curtisii, Bristle Bent is abundant in the sandy heaths of south-western UK but shuns

Shropshire. It is usually blue-green and always densely tufted with awned florets. The palea is vestigial (check against Corynephorus canescens which has weird swollen-tipped awns).

Part 2 â&#x20AC;&#x201C; The spike inflorescence Last time, in Agrostis spp. Bents we met the grass panicle, in which the basic clusters of florets, the spikelets, are borne on the tips of branches. This branched inflorescence is perhaps the commonest type in grasses. But consider an ear of Triticum aestivum Wheat, preferably in the flesh, but here (fig. 1) one is photographed from the side, twice, at right angles.

Two rows of spikelets are borne, sessile, on two sides of a completely unbranched inflorescence axis or rhachis. Each of the fan-shaped structures (on left ear) is a spikelet and if you take it apart it has a sterile boat-shaped glume (gl) at either end. In between are SEVERAL florets (not one as in Bents), each floret consisting of a lemma (le), similar in size and shape to the glume, and a palea (pa), essentially flat and tongue-shaped, with a grain in between, the matured ovary of the flower. This spikelet is thus manyflowered and much bigger than that of the Bents, but it would have to be, wouldnâ&#x20AC;&#x2122;t it, in order to have civilisations based on it! In some varieties the lemmas have quite long awns, and there Fig 1: two views of a wheat ear are also rare awned wheats such as Triticum turgidum Rivet Wheat which has more or less solid stems and glumes keeled to the base. Rye Secale cerale is essentially similar, but the glumes are very small, there are typically two florets in the spikelet and the lemmas are very long-awned.

This type of spike with two rows of spikelets on opposite sides of an unbranched rhachis is typical and is found in two of the commonest and most important grasses, Elytrigia repens Common Couch and Lolium perenne Perennial Rye-grass. The spike of Common Couch is built exactly like that of Wheat (they are actually quite closely related!) (Fig. 2). As in Wheat, the lemmas (and glumes) are sometimes awned (up to 4mm). It is of course a perennial, with vigorous wiry rhizomes which are the bane of gardeners. At either side of the ligule, at the junction of leaf sheath and leaf blade, are two auricles (pointed outgrowths) which are particularly fine and bristle-like. The leaves are usually fairly sparsely hairy.

Fig. 2: Two views of a Couch spike

Related species include several coastal plants, plus the woodland and woodlandmargin grass Elymus caninus Bearded Couch, which is tufted, without rhizomes and with conspicuous (up to 22 mm) awns on the lemmas.

The spike of Perennial Rye-grass is differently oriented to that of the couches or the wheats, having its two rows of spikelets in the same plane (Fig. 3). The spikelets typically have 4-11 flowers, borne in two rows, either side of a branch-like spikelet axis. There is only one glume; the one which would have been pressed against the rhachis has been lost. It is a mediumsized (typically 40 cm in fruit) shinyleaved glabrous grass, with (rather illdefined) auricles and typically red-tinged sheaths. The youngest leaf emerges from the shoot folded double rather than rolled. A grassland native, it is beloved of farmers because of its enthusiastic response to fertilisers and it is the main species in the sown leys.

Lolium multiflorum Italian Rye-grass is a similar, frequently-cultivated annual or biennial grass with very well-marked awns on the lemmas, with more florets (10-18) per spikelet and with the youngest leaf emerging rolled rather than folded from the shoot. Its common hybrid with perennial Rye-grass also has rolled young leaves and an intermediate number of florets and development of awns and rather reduced fertility. Lolium temulentum Darnel, is a probably Fig. 3 Part of a Rye-grass spike extinct annual weed with the glume longer than the spikelet.

Sometimes you may find a Rye-grass-like inflorescence which DOES actually have an inner glume against the rhachis. If growing in damp pasture with Rye-grass and/or Meadow Fescue Schedonorus pratensis, it could be the intergeneric hybrid between the two which Stace now says we must call X Schedolium loliaceum The Hybrid Fescue. Usually the spikelets are quite narrow and cylindrical compared with those of Rye-grass and they tend to spread widely out from the rhachis. Often there is the odd branch near the base of the inflorescence. And be aware of a tiny annual which is starting to appear close to busy roads in the Midlands. This is Catapodium marinum Sea Fern-grass. Usually there will be the odd double spikelet at a lower node.

I would also like to include at this point the Brachypodium sylvaticum False Brome, a large grass common in old woodland (and in limestone grassland). Tufted and with broad leaves, it has fairly uniformly hairy shoots (without auricles) and a nodding, unbranched inflorescence with two rows of of huge (2-4 cm-long), rather less clearlyoriented spikelets with awns as long as the lemmas. The spikelets are actually very shortly stalked and this inflorescence is therefore technically a raceme rather than a spike. You might keep an eye open for the similar, but rather rigid, more shortly-

awned racemes of Brachypodium pinnatum Tor-grass, a strongly-rhizomatous grass abundant on the chalk downs but a rare adventive here There are a few spikes with only a single row of florets along the rhachis. The common one is Mat-grass Nardus stricta, the familiar bristle-leaved grass with thickened leaf sheaths found in moorland and damp heaths. The spikelet is oneflowered, the lemma tapering into an awn and the glumes are tiny. The tiny ephemeral grass of coastal dunes, Mibora minima also has 1-sided spikes.

Grasses which appear to have unbranched inflorescences but are cylindrical with spikelets all around the rhachis, in the UK all have shortly-stalked spikelets and count as Spike-like-panicles rather than spikes, of which more next time! One group in which the inflorescence looks fairly cylindrical which we should include here are Hordeum spp. Barleys. Although the Hordeum inflorescences (Fig. 4), dominated

Fig 4 Wall (left) and Wood Barley

Fig 5 Wall barley spikelet cluster

by long awns, LOOK cylindrical, if you take them to pieces they consist of two opposite rows of clusters of three, one-flowered spikelets. Fig. 5 shows a single such 3-spikelet cluster from Hordeum murinum Wall Barley, that common annual denizen of pavements and rough urban grass. Up the middle is the awned lemma of a single floret, attended either side by its two darker, flat glumes to form a one-flowered spikelet. Either side again are the lateral florets, attended by their own pair of glumes.

The perennial grass of old pastures Hordeum secalinum Meadow Barley is rare in Shropshire. It can usually easily be told by its narrower inflorescence and because the glumes are bristle-like throughout and lack the flat basal portion seen in Fig. 4. The beautiful woodland Hordelymus europaeus Wood Barley has flattened glumes, fused at the base and is much taller than Wall Barley and also clearly a perennial. Also look out for the rare, annual Hordeum jubatum Foxtail Barley with a feather-like ear with extremely long awns.

In Barleys usually only the middle one of the three spikelets is fully fertile. This can be seen very clearly in the commonly cultivated Two-rowed Barley Hordeum distichon in which the grains form in the middle spikelets and the lateral spikelets are tiny. Be aware however of Six-rowed Barley Hordeum vulgare.

Part 3 – Spike-like Panicles Except for the spike inflorescences discussed last time (Autumn 2012 Newsletter), grass inflorescences are almost all panicles: branched, with spikelets1 on the end of the branches. However, in a few grasses, the branches are so short that the inflorescence axis appears unbranched. These are the spike-like panicles. The spikelets are never in the mandatory one or two rows either side of the axis found in the spikes and are usually arranged all around the axis to form a dense cylinder of spikelets (see Figs 5 & 6). You can usually detect the very short stalks to the spikelets with a bit of brutal dissection. If, however, bending an apparently unbranched inflorescence reveals some branches considerably longer than the spikelets, it should be sought amongst the grasses with panicles rather than those with spike-like panicles.

The most marginal species in this context is Anthoxanthum odoratum Sweet Vernalgrass (Fig. 1): Stace calls it a contracted panicle, both Hubbard and Cope & Gray a spike-like panicle. The inflorescence is often somewhat loose or even lobed in outline and occasionally the odd fairly lengthy branch may be found. It is however a very distinctive plant, a medium-sized, broad-leaved grass with a tuft of hairs (but also a marked membranous ligule) where the leaf sheath meets the leaf blade and of course with the wonderful scent of new-mown hay (the chemical; coumarin) when the shoot is crushed. The yellow-green inflorescences appear earlier than those of most grasses and herald the start of the hay fever season. The spikelets are very large: three florets are contained between the two glumes and the longer glume is almost a centimetre long. Particularly late in flowering you may be able to find quite prominent awns, attached at the base of the florets and bent in the middle (kneed or geniculate). It tolerates and is often abundant in a wide range of grassland and heathland habitats, from wet to fairly dry, from acid to fairly base-rich, and even shady or lead and zinc contaminated sites. It is however much less common in typical amenity grassland and in residential areas generally, although it is easily introduced in seed mixtures and lawns made with turf. A perennial, there is a very similar rare and decreasing annual neophyte, Anthoxanthum aristatum, of arable and sandy places, not I think ever recorded in Shropshire.

Cynosurus cristatus Crested Dog’s-tail (Figs. 2-4) is also a bit unusual in this group.

The inflorescence is a tight, cylindrical spike-like panicle but the spikelets are all thrown to one side with the main axis of the panicle clearly visible up one side of the cylinder. Among the clusters of spikelets, completely sterile many-flowered spikelets resembling little feathers cover much chunkier fertile several-flowered spikelets.

Florets have short awns on the ends of the lemmas. A small to medium–sized grass found throughout Shropshire, Cynosurus cristatus is a constant species in old meadows and pastures and also in semi-improved grassland, on a wide range of soil types. Sometimes, however, you can search a monad all day and only see its distinctive inflorescence once or twice, sometimes in clearly secondary habitats.

There is a longer-awned annual neophyte relative, Cynosurus echinatus Rough Dog’stail, with more ovoid inflorescences, a casual of bare places, once recorded in Shropshire.

1

The spikelet is the characteristic cluster of one or more florets, subtended by two sterile chaffy bracts known as glumes, found in grasses. Each floret consists of ovary and three stamens enclosed between two more chaffy bracts known as the lemma and the (usually smaller) palea. Lemmas, and less often glumes and paleas, may bear whisker-like bristles known as awns.

1. Anthoxanthum odoratum x2

2. Cynosurus cristatus x1/2

3 & 4 Cynosurus cristatus: two kinds of spikelets x 10

Two main genera of grasses have dense, cylindrical spike-like panicles in which the spikelet consists of a single floret concealed between the two glumes. They are Alopecurus the Foxtails and Pheum the Catâ&#x20AC;&#x2122;s-tails or Timothys. In Figs 5 & 6, the spike-like panicles and the spikelets of the two commonest species, Phleum pratense Timothy and Alopecurus pratensis Meadow Foxtail are illustrated. These are both modestly tall grasses, around 1 metre in flower, with the inflorescences around 75 mm. long and 7.5 mm wide. The essential differences are in the spikelet structure and such inflorescences should always be examined carefully since they are often superficially very similar, especially when covered in stamens. However Meadow Foxtail flowers from May and Timothy mainly from July.

5. Phleum pratense x1/2

6. Alopecurus pratensis x 1/2

In genus Phleum the two equal glumes have stiff hairs along the keel like a comb and are abruptly drawn out into short, stiff, tapering awns, giving the flattened spikelet the look of one end of a Mermaidsâ&#x20AC;&#x2122;s Purse.. The floret within is completely hidden. In

genus Alopecurus the glumes are also keeled, but are uniformly hairy and taper conventionally to a point. The single floret within has a fine awn which in most species protrudes clearly from between the two glumes (Fig. 7).

7. Spikelets of Alopecurus pratensis (left) and Phleum pratense (right) x10

In Shropshire Phleum is represented by two closely-related native species.

The larger is Phleum pratense Timothy and the smaller Phleum bertonolii Smaller Cat’s-tail. Both are typically components of neutral grasslands but Timothy consists mainly of many cultivars and often indicates past re-seeding. It is named for Timothy Hansen, who cultivated it widely in America and re-introduced it to UK in the 18th century.

Smaller Cat’s-tail grows mainly in old grassland on less fertile sites although it does include cultivars. No single character separates the two (except chromosome number) but they are separable by the combination of features in Table 1.

Table 1 Distinguishing Phleum pratense from P. bertolonii (from Cope & Gray) Character Phleum pratense Phleum bertolonii Plant height Mostly >70 cm Mostly <70 cm Leaf breadth Mostly >4 mm Mostly < 5 mm Anther length Mostly >1.7 mm Mostly <1.7 mm Panicle breadth Mostly >7 mm Mostly <7 mm Length of spikelet + awns Mostly >4 mm Mostly <4 mm Length of awn Mostly 1.2 mm or more Mostly less than 1.0 mm Chromosome number 2n = 42 2n = 14 .

There are other species in sand dunes (P. arenarium), the Brecklands (P. phleoides) and mountains (P. alpinum) which are not known in Shropshire.

There are four species of Alopecurus known from Shropshire (plus one other coastal (A. bulbosus) and one alpine (A.magellanicus) not known here). Alopecurus pratensis Meadow Foxtail is the largest and commonest. It grows as a perennial grassland plant and also lurks in many marginal habitats. It likes moist, heavy soil and avoids acid sites. Alopecurus geniculatus Marsh Foxtail is a smaller perennial (typically 20-30 cm in flower) and is made up of prostrate stems rooting at the nodes.

These turn upwards abruptly at a node when flowering, giving a very typical ‘kneed’ appearance. The spike-like panicles are smaller than those of Meadow Foxtail, although sizes overlap, and the glumes of an individual spikelet are blunt not pointed and much more shortly hairy. It is very common in winter-flooded places from the muddy edges of ponds to wet arable land, usually in sites at least modestly nutrientand base-rich. Alopecurus aequalis Orange Foxtail (Fig. 8) is a Shropshire axiophyte found characteristically in the draw-down zones of ponds. It is an annual or short-lived perennial and can remain in the seed bank for many years should water levels remain high. It is similar in scale to Marsh Foxtail, if rather more delicate, and is distinguished by its pale, glaucous stems and anthers opening bright orange.

However the anthers of Marsh Foxtail can by pretty orangey-brown and you should bend the inflorescence and look for awns â&#x20AC;&#x201C; they are very short and do not protrude from the spikelet in Orange Foxtail. Alopecurus myosuroides Black-grass (Fig. 9) is an annual of open, disturbed situations which became a dreaded weed of cereal crops in SE England due to the use of selective weedkillers. Up to 90 cm tall and erect, it produces spike-like panicles which are relatively longer and narrower than in the other species, giving it a more streamlined look. The glumes are narrowly winged along the keel and united at the base for at least a third of their length (much more shortly in other species). Scarce in Shropshire, look for it in towns and allotments as well as in arable.

8. Alopecurus aequalis (D Wrench)

9. Alopecurus myosuroides

10.Setaria viridis x1 (Anne Daly)

Aira praecox Spring Hair-grass, the tiny winter annual of drought-liable places in heaths, moorland and on rock outcrops, has spike-like panicles but is unlikely to be mistaken for any of the others. Each spikelet contains two florets, each with quite a long awn arising half way down the lemma.

Two genera of annual and short-lived perennial species adventive in Shropshire also include species with cylindrical spike-like panicles superficially similar to those of Phleum and Alopecurus. Polypogon monspeliensis Annual Beard-grass has a cylindrical spike-like panicle covered in long silky awns similar in proportion to those of Meadow Foxtail but the awns are born on both of the glumes not from between the glumes. Setaria the Bristle-grasses (Fig. 10) include several species with bristly cylindrical spike-like panicles The bristles are however not awns and can easily be seen to arise at the base of the spikelets. There are several species and Stace and Cope & Gray both provide adequate keys. Lagurus ovatus Hareâ&#x20AC;&#x2122;s-tail, a cultivated annual, has an ovate spike-like panicle rendered beautiful by bristle-like glumes covered in white, silky hairs.

Part 4.1 â&#x20AC;&#x201C; The clearly-branched Panicles In most grasses the inflorescence is clearly branched and therefore by definition clearly a panicle. The branching and the arrangement of the panicle is often characteristic, but the overall shape usually changes through the flowering period, so that in most cases we need to examine the spikelet (the structure borne at the end of each branch) for a definitive identification.

Agrostis vinealis Brown Bent (x 1)

Calamagrostis epigejos Wood Small-reed (x 3)

Briza media Quaking-grass (x 1)

Festuca rubra Red Fescue (x 1)

Some examples of grass panicles

The Grass spikelet The basic unit of the inflorescence, borne at the end of each branch. It consists of either a single floret (i.e. a small flower) or a tight cluster of florets, in either case with two sterile bracts at the base called the glumes. The floret often bears an awn, a fine bristle, usually attached to the lemma, the outermost scale of the floret. The spikelet varies greatly in size. In Rye Brome Bromus secalinus it is 1-2 cm long but in the Bents Agrostis spp. it is only 2-3.5 mm long:

floret

Spikelet of Agrostis stolonifera Creeping Bent (2-3 mm long)

Spikelet of Bromus secalinus Rye Brome (10-20 cm long excluding the awns) glume

Two examples of spikelets ×3; grid squares are 1mm x 1 mm Spikelet form also changes: when the anthers are shedding pollen (anthesis), the spikelet (and the florets) typically gape open and when the fruit forms, the spikelet often closes up again. Early in the season the florets overlap, folded into one another; later they usually become more separate and distinguishable and late in the season they may drop, leaving only the empty glumes still present. Nevertheless, much identification can be achieved based on the number of florets in the spikelet, the relative lengths of glume and the floret or florets, and the disposition and type of awn: The main types of spikelet in grasses with clearly-branched panicles 1. Glumes clearly longer than the florets and typically enclosing them at least before anthesis; if the florets are awned, awn usually dorsal (borne on the back) or basal (near the base) on the lemma and geniculate (bent in the middle) 2. Spikelets essentially 1-flowered, awned or not ………….....GROUP 1 2. Spikelets mostly 2-3 flowered, one or more floret(s) almost always with a dorsal geniculate awn…………………………………….....…..GROUP 2 1. Glumes, (usually both), shorter than the florets; if the florets are awned, awn attached at or near the tip of the lemma, awns more or less straight 3. Spikelets of essentially one floret ………………………….GROUP 3 3. Spikelets many flowered, florets typically in two symmetrical rows one on each side of a hair-like axis or rhachis………………………... GROUP 4

GROUP 1 Glumes clearly longer than the florets and typically enclosing them at least before anthesis; spikelets essentially 1-flowered. If the florets are awned, the awn is usually borne on the back or near the base of the lemma and bent in the middle.

Agrostis stolonifera

Phalaris arundinacea

Milium effusus

Calamagrostis epigejos

Group 1 spikelets. Phalaris and Milium shown with and without glumes, Calamagrostis only without glumes. All Ă&#x2014; 8; Grid is of 1 mm Ă&#x2014; 1 mm squares.

All Bents Agrostis species fall into this category; their many-branched panicles, rather like 3-dimensional feathers, all have tiny single-flowered spikelets circa 2-3 mm long and were described in part 1 of this series. In some species the lemma bears a dorsal or basal awn.

Reed canary-grass Phalaris arundinacea, is a common, tall, broad-leaved reed-like waterside plant but with a membranous ligule and with a large panicle of denselyclustered spikelets with keeled glumes (other Phalaris spp. have spike-like panicles).

Wood-millet Milium effusum is a large elegant old woodland grass with a large, longbranched panicle and florets producing shiny, millet-like grains.

Small-reeds Calamagrostis are large grasses distinguished by the long hairs sprouting from the base of the floret (usually longer than in the photograph). Wood Small-reed Calamagrostis epigejos occurs mostly in woodland margins (also post-industrial sites) and Purple Small-reed C. canescens in shaded or unshaded mires. The latter has a shorter ligule and the upper surface of the leaf blade is hairy; the inflorescence also tends to droop to one side. Neither is common and the latter is distinctly uncommon.

GROUP 2 Glumes (at least one) clearly longer than the florets and typically enclosing them except at anthesis; Spikelets mostly 2-3 flowered, one or more floret almost always with an awn attached on the back of the lemma, awn typically bent in the middle This is a large group of at least eight genera in Shropshire; also the spike-like panicle of Sweet Vernal-grass Anthoxanthum odoratum is sometimes sufficiently branched to go in the panicle group and would then key out here. Ignoring Anthoxanthum odoratum (see part 3 Autumn 2013), three types of spikelet are seen in Group 2: The first type comprises only the little blue-green grass of heathland, acid grassland and limestone pasture (???) Heath-grass Danthonia decumbens. This has spikelets more resembling those of Group 4 but the floret group is exceeded in length by both glumes. It also differs from the others in Group 2 in that all the lemmas are awnless and the ligule consists entirely of hairs.

The rest of Group 2 (except cultivated Oat) have at least some florets with (usually dorsal) awns. In second group, the ‘Oats and Oat-grasses’, these awns are conspicuous and protrude well beyond the glumes. In the third group, ‘Soft-grasses and Hair-grasses’ the awns are less conspicuous and often protrude little or not at all.

The awns are moderately conspicuous in Wavy Hair-grass, but it is the only perennial in Group 2 with bristle-like, as opposed to flat, leaf blades.

The Oats and Oat-grasses include five genera: 1. Annuals with pendulous spikelets 2-3 cm long…………………….. Oats Avena 1. Perennials with non-pendulous spikelets circa 1 cm long or less…………………..2 2. Spikelets circa ½ cm long long…………. Yellow Oat-grass Trisetum flavescens 2. Spikelets circa 1 cm long……………………………………………………...…3 3. Each floret with a geniculate dorsal awn, spikelet more than 1 cm long ………………………………………….Downy Oat-grass Helictotrichon pubescens 3. One floret with a geniculate dorsal awn, the other with awn weak and straight or absent, spikelet up to 1 cm long ………………False Oat-grass Arrhenatherum elatius

Danthonia decumbens

Avena fatua

Helictotrichon pubescens

Arrhenatherum elatius

Trisetum flavescens

Spikelets of Heath-grass and Oatgrasses. Avena fatua ×2, others ×3 (1mm grid) (Arrhenatherum elatius and Trisetum flavescens shown with and without glumes) Cultivated Oat Avena sativa, in common with most cereals has spikelets which do not break up and disperse at maturity. It usually lacks awns and the florets are smooth. It may occur as a weed.

Wild-oat Avena fatua is a common weed of crops and waste land, the florets are awned and bear conspicuous stiff forward-pointing hairs, especially near the base.

The spikelet breaks up into individual florets at maturity. There are other Wild-oats which break up differently than in Avena fatua, but they are not recorded in Shropshire.

Yellow Oat-grass Trisetum flavescens is a small grass of unimproved grassland with shoots usually beset with sparse, downwards-pointing hairs. The spikelets are glossy yellow or golden, 2-4-flowered and it is the smallest of the grasses with prominent dorsal geniculate awns.

False Oat-grass Arrhenatherum elatius is an almost ubiquitous coarse, slightly hairy grass, always recognisable from its bright yellow roots.

Downy Oat-grass Helictotrichon pubescens is even hairier-leaved than A. elatius and is specific to old neutral or calcareous grassland. Its larger spikelets than those of Arrhenatherum, with two or more geniculate awns per spikelet, give it away. We are still looking for Meadow Oat-grass Helictotrichon pratense on the Shropshire limestones. The spikelet has three or more florets and the leaves are stiff and glabrous.

In the Soft-grasses and Hair-grasses, the third type within Group 2, the spikelets are typically smaller than in all the Oat-grasses except for Yellow Oat-grass Trisetum flavescens, i.e. ½ cm long or less. Except in the bristle-leaved Wavy Hairgrass Deschampsia flexuosa, the awns are much less conspicuous than in the Oat-grasses and often protrude little or not at all from between the enclosing glumes. The spikelet always consists of two florets.

Aira caryophyllea

Deschampsia cespitosa

Deschampsia flexuosa

Holcus lanatus

Holcus mollis

Spikelets of Hair-grasses and Soft-grasses x5 (all shown with and without glumes) Silver Hair-grass Aira caryophyllea is a delicate little winter annual of droughty, slightly base-enriched substrates. It is usually taller but with smaller spikelets than Early Hair-grass Aira praecox which has spike-like panicles. In both, there are two florets, both bearing a very fine dorsal geniculate awn. At maturity the silvery hue and the open panicles of A. caryophyllea are usually very striking.

Wavy Hair-grass Deschampsia flexuosa is abundant or even dominant in many acid grasslands and heaths and open woodlands. In heathland the shiny, coppery-red glumes and the long, crimped branches of the panicles are usually very characteristic, but the colour may be more silvery in woodlands. It is quite strongly awned, but unlike the rest of Group 2 it is a bristle-leaved perennial, distinct from the other perennial bristle-leaved grasses Mat-grass, which has basal cushions of sheaths and one-sided spikes and the bristle-leaved fescues (Festuca ovina and rubra), which have Group 4 panicles and chocolate-brown roots (white in D. flexuosa). (Druce recorded the very similar but much rarer Deschampsia setacea at the meres in the 19th century).

Tufted Hair-grass Deschampsia cespitosa forms large, dense tussocks of sharpedged leaf blades in a variety of impeded drainage situations (included in shade) and also in limestone woodland. The panicles can be striking, up 50 cm long on tall stems. Woodland variants with smaller (3 mm) spikelets may be subsp. parviflora.

In the Soft-grasses (Holcus spp.), the panicles are relatively dense and manyspikeleted compared with those of the Hairgrasses and two conspicuous papery, strongly keeled glumes enclose the two florets except for the tip of the awn.

Yorkshire Fog Holcus lanatus, almost ubiquitous, is possibly our commonest grass.

It is tufted, softly hairy and one of the two florets has a hooked awn from near the tip of the lemma; the awn can often be seen projecting sideways between the glumes.

Creeping Soft-grass Holcus mollis is also a very common grass, especially in woodlands; it is shade-tolerant but restricted to fairly acid substrates. Unlike Yorkshire-fog it has a formidable rhizome underground and it is usually almost hairless except for conspicuously bearded nodes (‘hairy knees’). The awn is more clearly dorsal than in H. lanatus, protruding beyond the tips of the glumes and straight not hooked. Cope and Gray say that there are sterile hybrids which resemble H. mollis but are more hairy and have shorter, less exserted awns.

GROUP 3 At least one, and usually both, glumes shorter than the florets, spikelets essentially of one floret; if the florets are awned, awn attached at or near the tip of the lemma, more or less straight

Melica uniflora

Panicum miliaceum

Spikelets with glumes shorter than floret and with essentially a single floret . Both × 5 Wood Melick Melica uniflora is the only grass in this group which is at all common in Shropshire. Even in this species there is a small clump of tiny sterile lemmas as well as the single fertile floret in the spikelet. The chunky spikelets are borne sparingly on long, bare branches. A medium to small grass typical of old woodlands and shade on modestly base-rich soils, sometimes on shallow soils or even rock outcrops. Mountain Melick Melica nutans has a spikelet with several fertile florets and falls in Group 4.

The Millets and Cockspur (Panicum and Echinochloa) are uncommon casuals with chunky, mostly awnlesss single florets of the type shown (vaguely!) in the figure: rather onion-like, with two small glumes at the base. The inflorescence type varies tremendously, but the leaf ligule consists of hairs or there is no ligule at all.

Loose Silky-bent Apera spica-venti and Dense Silky-bent Apera interrupta have also been recorded as casuals; The single floret has a fine dorsal awn 5+ mm long; One glume is the same length as the floret, only one is shorter than the floret.

Whorl-grass Catabrosa aquatica usually has 2 or 3 florets, so will be included in Group 4.

GROUP 4 Glumes both shorter than the florets, spikelets many flowered, florets typically in two symmetrical rows one on each side of a hair-like axis or rhachis; if the florets are awned, awn attached at or near the tip of the lemma, ± straight

This is another large group, including the genera Briza, Bromus, Catabrosa, Catapodium, Dactylis, Festuca, Glyceria, Melica nutans, Molinia, Phragmites, Poa, Puccinellia and Vulpia. We will tackle Group 4 next time if allowed!

Part 4.2 – the fourth and final group of the clearly-branched Panicles In the Autumn 2014 issue of the Newsletter, four groups of grasses with clearlybranched panicles were distinguished, based on the prominence of the glumes and the number of flowers in the basic unit of the grass inflorescence, the spikelet.

Here we are dealing with the last of the four groups, in which  the glumes are both shorter than the florets, exposing the florets to view  the spikelets has many florets In these grasses, the spikelets are typically flattened structures in which the florets are in two symmetrical rows one on each side of a hair-like axis or rhachis. If the florets are awned, the awn is attached at or near the tip of the lemma, and is ± straight.

rhachis glumes

awns

florets Spikelet of Barren-brome Anisantha sterilis (scale in mm) This is a very common form of spikelet in grasses. The same type of spikelet can also be seen in the grasses in which the inflorescence is an unbranched spike (e.g. in the Ryegrasses Lolium spp. and in Couch Elytrigia repens) or a spike-like panicle (e.g. in Crested Dog’s-tail Cynosurus cristatus).

There are about 50 species of panicle-forming grasses in this group! Some are very distinctive: Fern-grass Catapodium rigidum This little (typically 15 cm or less tall at flowering) winter annual will be found fruiting in spring and early summer in infertile, droughty places such as quarry ledges, spoil tips, tops of garden walls, pavements, stone steps.

The panicle branches in one plane, with shortly-stalked clusters of spikelets at each node, all facing to one side of the panicle. Each spikelet is long and narrow with as many as ten florets. There are no awns. The whole is rather stiff and rigid until it breaks up at maturity. We dealt with its salt-tolerant relative Sea Fern-grass Catapodium rigidum with the spikes, since its inflorescence is essentially unbranched.

Water Whorl-grass Catabrosa aquatica. Usually less than 30 cm tall, this uncommon grass produces a 10-20 cm purplish panicle of densely-clustered whorls of branches spaced at fairly wide intervals. The distinctive spikelet typically consists of

only two blunt florets, but the two glumes are much shorter (lens), differentiating it from the Bents Agrostis spp. with which it could be confused. It is found especially in open mud by ponds and in slow-running ditches.

Mountain Melick Melica nutans Found in the margins of a very few of our old, base-rich woods, this close relative of the Wood Melick has similar awnless chunky spikelets but arranged on short stalks in an otherwise almost (but not quite) unbranched, nodding raceme-like inflorescence. Two to three florets project beyond the glumes.

Quaking-grasses Briza spp. The utterly distinctive, laterally-flattened manyflowered spikelets of the Common Quaking-grass Briza media, borne drooping in panicles and quaking in the wind are a pleasing feature of many base-rich habitats from dry limestone through old hay meadows to base-flushed mires. Similar but much larger (1.5 – 2.5 cm long) spikelets are seen in the annual garden escape Greater Quaking-grass Briza maxima.

Common Reed Phragmites communis This giant reedswamp-forming grass is unmistakable, but its ligule, where the leaf sheath meets the leaf blade, is of hairs, distinguishing it from the other reedswamp-forming grasses Reed canary-grass Phalaris arundinacea and Reed Sweet-grass Glyceria maxima which have membranous ligules. The inflorescence forms late and the spikelet looks 1-flowered until early Autumn, when it opens to reveal a group of long-pointed florets mixed with long, silky hairs.

Purple Moor-grass Molinia caerulea Like Phragmites, this grass also has a ligule reduced to a fringe of hairs. It forms dense tussocks surrounded by last years dead, whitish leaves and produces beautiful spreading sprays of rather narrow panicles in summer. It is associated with a wide range of heath and mire habitats and is an annoying coloniser of insufficiently-wet mires. The medium-sized (c. 0.5 cm) spikelet has 3 or 4 rather loosely-arranged, pointed but not awned, florets.

Cock’s-foot Dactylis glomerata This ubiquitous coarse grass tends to form untidy tussocks in un- or under-grazed grassland and other grassy places, especially where the soil is fertile. The whitish non-flowering shoots are broad and curiously flattened, generating strongly-folded leaf blades which are 1 cm. or more wide when flattened out. The tip of the panicle is lobed but rather spike-like, but there are a few long bare branches below, each producing dense, lobed masses of spikelets above. This form is not seen elsewhere, except it is sometimes approached in Reed Canary-grass Phalaris arundinacea,, which is quite different vegetatively and has one-flowered spikelets.

The spikelet in Cock’s-foot is ½- 1cm long, wedge-shaped and the lemmas of the florets are sharply keeled on their backs and drawn out into sharp points or short awns.

The rest of the grasses with panicles in which the spikelets are many flowered and the glumes are both shorter than the florets comprises of four genera groups, some with various satellites and segregates. They may be distinguished critically as in the key below: Semi-diagnostic key to main groups of grasses with panicles of many-flowered spikelets and glumes both shorter than the florets 1. Ovary surmounted by a lobed, fleshy terminal

appendage, the styles arising from beneath it……………………………………………….

1. Ovary hairy or not but without an appendage, styles terminal on the ovary………………..

2. Leaf sheaths cylindrical, lemmas awnless……

2. Leaf sheaths open, their margins overlapping, if fused almost to the top then lemmas awned at or near the tip………………………………

The Bromes Bromus, Bromopsis, Anisantha and Ceratochloa 2 The Sweet-grasses Glyceria spp.

3.

3. Lemmas rounded on the back, at least below..

The Fescues Festuca spp., Schedonorus spp.

Vulpia spp, (plus Puccinellia)

3. Lemmas keeled throughout………………….

The Meadowgrasses Poa spp.

Meadow-grasses Poa spp.

The spikelets have a very characteristic sharp-edged oval outline because the backs of the lemmas are sharply keeled and there is a complete lack of awns, but in most species the spikelet is small (often less than 0.5 cm long) and there may not be many flowers in the spikelet , so that, especially early in flowering, you might need to look with a lens to be sure it is a Poa rather than an Agrostis. The inflorescence is usually a neat cone, tapering to a point above, with many branches and many spikelets. The leaf-sheaths are keeled and flattened and the leaf blades keeled with a characteristic tip shaped like the prow of a boat.

Meadow-grasses are found in most habitats; several species such as Rough Meadowgrass Poa trivialis and Annual Meadow-grass Poa annua are almost ubiquitous and seven other species recognised in Stace have been recorded in Shropshire: Broad-leaved Meadow-grass P. chaixii; Flattened M-g P. compressa; Spreading M-g P. humilis; Wood M-g P. nemoralis, Swamp M-g P. palustris; and Smooth M-g P. pratensis .

Spikelet of Glyceria plicata x 5 Spikelet of Poa humilis x 8

Sweet-grasses Glyceria spp.

Aquatic or marsh perennials with medium to large (0.5-3.5 cm. long), often very numerous-flowered spikelets, in which the lemmas are rounded on the back, fairly blunt at the tips and without awns. The leaf-sheaths are fused into a tube and are often keeled and the broad leaf-blades quite sharply folded; the foliage is luscious and eagerly grazed.

Reed Sweet Grass Glyceria maxima is one of our major reedswamp-forming species in the margins of rivers and canals, particularly on richly-fertile substrates. Three related species and one hybrid of lesser stature are widely distributed in wetlands: Floating Sweet-grass Glyceria fluitans; Small S-g G. declinata; Plicate S-g G. notata and Hybrid S-g G. x pedicellata.

Fescues Festuca sensu lato In Stace these are segregated into three genera. The annual species are placed in a separate genus Vulpia in which the relatively narrow lemmas narrow imperceptibly into awns longer than the rest of the lemma. In Shropshire in this group we have Squirreltail Fescue Vulpia bromoides and Rat’s-tail Fescue V. myuros.

Vulpia and Festuca species mostly have narrow leaves which are habitually folded up into bristles almost cylindrical in section. The genus Festuca in its sense in Stace consists mainly of medium-sized to small perennial bristle-leaved grasses with panicles which are much less branched than in Meadow-grasses and with larger spikelets, and florets with pointed and usually terminally-awned lemmas. The key species are Red Fescue Festuca rubra and Sheep’s-fescue Festuca ovina which are important constituents of semi-natural grasslands. The other species and well-marked subspecies in Shropshire are Wood Fescue Festuca altissima (a rare, flat-leaved species); F. rubra subsp. commutata; F. rubra subsp. megastachys; Confused Fescue F. lemanii; Hard Fescue F. brevipila and Fine-leaved Sheep’s-fescue F. filiformis.

Most of the flat-leaved fescues have prominent pointed auricles (moustache-like outgrowths either side of the leaf ligule). These have been segregated into the genus Schedonorus. In Shropshire we have Tall Fescue Schedonorus arundinaceus; Giant Fescue S. giganteus; and Meadow Fescue S. pratensis

Keying out with the fescue genera, but not so closely related, is Puccinellia, a genus of saltmarsh grasses which are represented in Shropshire by Reflexed Saltmarsh-grass Puccinellia distans, found mainly by roadsides and on (presumably saline) spoil tips.

The spikelet is small (c. 0.5 mm), the lemmas rounded on the back unlike in Poa and unlike in Festuca the lemma has a blunt, unawned tip.

The Bromes Bromus sensu lato These have often been placed in the single genus Bromus, united by the mysterious appendage on top of the ovary with the stigmas arising beneath it, which is visible from first flowering all the way to fruiting (lens, or preferably stereo microscope, but worth looking for if you are not sure whether you have a Brome or a Fescue!). This feature is only shared by the False-bromes Brachypodium and in a small way by the Wheats and Barleys. Otherwise the Bromes resemble the larger, flat-leaved, Fescues, but in the Bromes the leaf sheaths are usually hairy and their awns (which all ours have) are usually clearly subterminal on the lemmas which are often prolonged beyond into two small points. The spikelets are always fairly (or very) large.

Most modern treatments segregate them into four genera. The large, broad-leaved perennials form genus Bromopsis, with three species in woodland and calcareous grassland in Shropshire. Hairy-brome Bromopsis ramosa; Lesser Hairy-brome Bromopsis benekenii and Upright Brome Bromopsis erecta.

The introduced American Bromes Ceratochloa are short-lived perennials at most, and recognisable by their large awned spikelets which are strongly compressed with the lemmas keeled as in Poa (but awned and much larger: 3 cm long plus awns). Two have been described from Shropshire and one, California Brome Bromus carinatus seems to be increasing. Rescue Brome Ceratochloa cathartica is uncommon.

The rest are all annuals. The Barren-bromes Anisantha have huge parallel-sided spikelets, gaping at maturity, with awns longer than the lemmas. The genus includes that terror of selective-weedkiller-using farmers Barren-brome Anisantha sterilis and, with even larger spikelets, the uncommon Great Brome Anisantha diandra.

The Bromes, Bromus in the strict sense, have more moderately large spikelets, ovate to lanceolate in shape and the awns are shorter than or about as long as the lemmas.

The Soft-brome Bromus hordeaceus, common especially in disturbed or trampled ground, has softly hairy spikelets, most of the rest are uncommon or rare and mostly have glabrous spikelets: They are Meadow Brome Bromus commutatus; Lesser Softbrome Bromus hordeaceus subsp. pseudothomininii; Smooth Brome Bromus racemosus and Rye Brome Bromus secalinus.

Spikelet of Festuca rubra x 5 Spikelet of Bromus secalinus x2 References Consult the following for further information, illustrations etc.

Cope, T. & Gray, A (2009) Grasses of the British Isles. BSBI Hubbard, C.E. (1984) Grasses ed. 3..Penguin Books Stace, C. (2010) New Flora of the British Isles ed 3. Cambridge