Bromus arenarius Labill., Nov. Holl. Pl. 1: 23, t. 28 (1805).

Serrafalcus arenarius (Labill.) C.A.Gardner, Fl. W. Australia 1: 96 (1952). T: in Terrâ Van-Leuwin

Vegetative form. Annual, caespitose. Leaves scattered along the culms. Culms 14.5-48 cm high, unbranched above, 3 noded. Mid-culm nodes hairy (darkly pigmented and sunken). Mid-culm internodes hollow, glabrous (becoming indumented in vicinity of the node, trichomes retrorse), terete. Young shoots intravaginal. Leaves non-auriculate. Basal leaf sheaths not keeled, terete, puberulous to pilose, without readily visible transverse veins, with margins connate, in lower 1/2 to in lower 2/3s, hyaline to membranous, ciliate. Ligule 1-1.5 mm long, hyaline, coarsely ciliolate, acute, erose to lacerate. Collar puberulous to pilose. Leaf blades flat, linear, 60-110 mm long, 1.5-4 mm wide; adaxially pilose; abaxially pilose; with margins ciliolate to with margins ciliate, apices acuminose, flat; conduplicate in bud.

Reproductive organization. Plants bisexual. Incomplete spikelets absent. Inflorescence of cleistogamous spikelets.

Inflorescence. Inflorescence a raceme or a panicle, open, straight (but lax). Main inflorescence axis 110-375 mm long. Peduncles 59-215 mm long, glabrous or puberulous (trichomes retrorse, becoming antrorse acropetally). Rachides 28-83 mm long, narrowly terete or strap-like to subterete, scabrous or puberulous to pilose (antrorse). 4-5 spikelets on the rachis. Rachis angles puberulous, or pilose (antrorse). Primary inflorescence branches reflexed (lax), acropetally opposite or verticillate (basipetally), sometimes with spikelets inserted at the base or without spikelets inserted at the base. Spikelets 0 per node, or 2-4 per node. Spikelets 1-2 on a typical ultimate inflorescence branch, on first order branches or on second order branches, solitary or grouped (only the proximal spikelets, considered by some to be borne on inflorescence branches), reflexed (lax).

Hermaphrodite (`perfect') spikelets. Hermaphrodite spikelets pedicellate, 19-35 mm long (often varying on a single individual), laterally compressed, oblong or ovate to elliptic, disarticulating as a separate unit, disarticulating above the glumes. Pedicels 15-25 mm long. Glumes two per spikelet, free, similar, subequal, lateral to the rachis. Lower glume c. 3/4s the length of the upper glume, narrowly elliptic to narrowly obovate, 8-8.5 mm long, 1.25-1.5 mm wide, chartaceous, slightly acropetally keeled or dorsally rounded, acuminate to acute, muticous, margin hyaline, margin smooth or margin ciliolate to margin ciliate; 3 veined, veins obscure, midvein scabrous to midvein puberulous or midvein pilose (sometimes only acropetally); intercostal regions pilose. Upper glume narrowly ovate to narrowly elliptic, 10-11.5 mm long, 1.5-2 mm wide, chartaceous, slightly acropetally keeled or dorsally rounded, shortly acuminate to acute, muticous, margin hyaline, margin smooth or margin ciliolate to margin ciliate; 5 veined, veins obscure, midvein scabrous to midvein puberulous or midvein pilose (sometimes acropetally only); intercostal regions glabrous, or intercostal regions puberulous to intercostal regions pilose. Incomplete florets present, distal to the hermaphrodite florets. Hermaphrodite florets 5-14 per spikelet. Rachilla disarticulating between the florets, disarticulating directly below the florets (callus scar circular), flexuous, scabrous to puberulous, elongated between all florets (the internodes inflated), apically prolonged. Callus present, blunt, 0.5 mm long, glabrous. Lemma similar in firmness to the glumes, narrowly elliptic or narrowly obovate to oblong, 12-13.5 mm long, 1.5-3 mm wide, chartaceous, not keeled, shortly acuminate to acute, shallowly emarginate, 2 -lobed, awned. Lemma margins smooth or scabrous to ciliolate. Lemma 7-8 veined. Lemma veins confluent towards the apex, obscure, connected by obscure transverse veins, pilose (sometimes minutely), with the hairs on all the veins, with the hairs extending the length of the veins or with the hairs only at the vein apex (sometimes); intercostal regions puberulous or pilose (sometimes minutely), the hairs over the entire dorsal surface. Awns 1, median. Median awn about as long as the body of the lemmas (longer in the distal florets), 9-14.5 mm long, 1 veined, dorsal, arising from the upper half of the lemma, straight or curved (outwards), scabrous. Palea fully developed, similar in texture to the lemmas, tightly clasped by the lemmas, narrowly ovate or narrowly elliptic to narrowly obovate, 9-10 mm long, 1.5-2 mm wide, membranous to chartaceous, 2-keeled, keels wingless, acute to obtuse, entire; 2 veined, veins pilose; intercostal regions puberulous. Lodicules 2, free, fleshy, acute, with entire margins, glabrous. Stamens 3. Anthers 1.5 mm long, basally 2-lobed, without a basally prolonged connective. Ovary with a conspicuous apical appendage, pilose, with the hairs only at the apex. Styles 2, free to their bases. Distal incomplete florets 2-4 per spikelet, neuter, merely underdeveloped, awned, paleate or epaleate.

Fruit. Fruit adhering to lemma and adhering to palea, oblong to elliptical, dorsiventrally compressed, 7-9 mm long, 1.5 mm wide, not grooved, puberulous, with dense hairs, the hairs confined to a terminal tuft. Hilum 5.75-6.5 mm long, linear. Embryo 1-1.5 mm long, not waisted.

Abaxial leaf blade epidermis. Leaf anatomical data recorded.

Costal/intercostal zonation conspicuous; the intercostal zones bordering the midrib 23-32 cells wide; epidermis differentiated into long- and short-cells; long-cells different in shape costally and intercostally (the intercostal long-cells straight-walled and fusiform; the costal long-cells rectangular with undulate walls); long-cells of similar wall thickness costally and intercostally.

Microhairs absent.

Crown cells absent. Prickles present (and abundant); intercostal and marginal; antrorse and retrorse; fairly uniform in size and form. Prickle bases not paired with a short-cell. Intercostal prickles in the astomatal files. Bases of the intercostal prickles shorter than the width of an intercostal long-cell to about as long as the width of an intercostal long-cell, or longer than the width of an intercostal long-cell; shorter than the stomata; barbs of the intercostal prickles up to twice as long as the bases to more than twice as long as the bases. Macrohairs present, or absent; intercostal; intergraded with long prickles; unicellular; lax, or robust; with thickened walls, or with thin walls; dense, or sparse but frequent; more than twice as long as an intercostal long-cell, or twice as long as an intercostal long-cell. Macrohair bases one-celled; attached at cuticle only; uniform in mode of insertion.

Intercostal long-cells fairly constant in shape. Mid-intercostal long-cells markedly elongated; fusiform; inflated, or hexagonal; long-cell walls straight; end walls vertical, or angled. Papillae absent.

The costal zones all histologically similar; costal short-cells conspicuously in long rows. Costal silica bodies present and perfectly developed; throughout the costal zones; horizontal-crenate and horizontal-smooth.

Intercostal short-cells infrequent, or absent; confined to the outer regions of the intercostal zones, or mid-intercostal only; solitary. Unsilicified intercostal short-cells square; walls straight. Intercostal silica bodies absent, or imperfectly developed; when present, cuboid.

Stomata common; present in all the intercostal zones; distributed throughout the intercostal zones; arranged in definite rows (but the rows intermittent). Stomatal rows in the widest intercostal zones 2-6; evenly dispersed, or bordering the costae. Stomata 47-54-69 m long; with guard-cells overlapped by the interstomatals. Subsidiaries dome-shaped to parallel-sided. The domes of medium height, or low.

Photosynthetic pathway and related features. C3. XyMS+. The PBS sheaths of the primary lateral vascular bundles interrupted. Mestome sheath single; complete.

Transverse section of the leaf blade. Lamina mid-zone in transverse section open; more or less flat, or more or less flat to rolled. Width of lamina across a primary vascular bundle 117-180-292 m. Lamina mid-zone in transverse section with ribs both adaxially and abaxially, or exhibiting adaxial ribs only; the adaxial and abaxial ribs opposite one another. Adaxial furrows slight; wide, or wide to narrow. Adaxial furrows between all the vascular bundles. Adaxial ribs more or less constant in size; round topped to flat-topped, or round topped; opposite all vascular bundles, or opposite all vascular bundles to opposite major vascular bundles only. Vascular bundles in the mid-lamina 11-23; 1 per rib. Abaxial furrows present between the vascular bundles, or absent. Abaxial ribs opposite major vascular bundles only; smaller than adaxial ribs.

Midrib pronounced in outline; adaxially raised and rounded; prominent abaxially; tissue layout similar to that of other primary vascular bundles. Vascular bundles in the mid-lamina region of the midrib 1. The median vascular bundle with a protoxylem cavity; with an enlarged protoxylem vessel; with sclerosed phloem. Midrib without colourless tissue adaxially, or with colourless tissue adaxially (the adaxial sclerenchyma as a strand); without lacunae. The lamina symmetrical on either side of the midrib.

Mesophyll chlorenchyma non-radiate; tightly packed. Mesophyll without lacunae; without any obvious adaxial palisade; without `circular cells'; not traversed by columns of colourless cells; without arm cells; without fusoids. Bulliforms of large cells absent as discrete groups but the epidermis extensively bulliform. Abaxial epidermis of bulliform-like epidermal cells. Abaxial epidermal cell walls not thickened. The cells irregular in shape.

The major vascular bundles interspersed with minor bundles; outlines of primary vascular bundles more or less circular; primary vascular bundles centrally situated. Primary lateral vascular bundles with adaxial sclerenchyma; with abaxial sclerenchyma; the adaxial sclerenchyma forming girders; the abaxial sclerenchyma forming girders; the combined girders nowhere forming `figures', or forming I's. Outlines of lower order vascular bundles more or less circular. Lower order vascular bundles centrally situated; with adaxial sclerenchyma, or without adaxial sclerenchyma; without abaxial sclerenchyma; the adaxial sclerenchyma forming strands, or forming girders; the smallest vascular bundles lacking sclerenchyma. The adaxial sclerenchyma of the mid-lamina all associated with vascular bundles.

Vouchers. Specimens examined morphologically: C.W.E.Moore 8456: "Mt ?Midydi", c. 8 km NW. of Louth (N.S.W.); 21.ii.1985; Fl.; NSW - C.W.E.Moore 8227: 6 km W. of Louth (N.S.W.); 4.x.1981; Fr.; CANB - C.W.E.Moore 6319: "Mt Mulyah"? c. 60 mls NW. of Louth (N.S.W.); 24.viii. 1973; Fl.; CANB - C.W.E.Moore 5447: "Wottagoona" c. 40 mls SE. of Louth; 24.viii. 1968; Fl.; CANB - A.Slee 696 & Holgate: Yathong N.R., via Mt Hope (N.S.W.); 2.xi.1985 Fl.; CANB - G.J.Keighery 216 & J.J.Alford: Whittell Is. between Green Is. & Buller Is. c. 2.5 km from the mainland (W.A.); 11.xii.1985; Fl.; CANB, PERTH - J.Z.Weber 8154: Gawler Rng., Mt Ive tank (S.A.); 18.x.1983; Fr.; CANB, AD - D.E.Symon 14059: Moralana Stn., South of bore paddock (S.A.); 10.x.1984; Fr.; CANB, ADW - J.Carrick 2308: Gawler Rng., near Kolendo c 20 km WNW. of Nonning, c. 120 km W. of Port Augusta (S.A.); 26.ix.1969; Fl.; CANB, AD - C.W.E.Moore 4529: 7 km S. of Bourke on Cobar Rd. (N.S.W.); 18.xi.1982; Fr.; CANB - R.W.Purdie 2095: 3 km E. of Port Augusta on the Woomera Rd. (S.A.); x.1981; Fr.; CANB - K.Paijmans 1652: 45 km NNW. of Hay (N.S.W.); 21.xi.1975; Fr.; CANB - N.Forde 912: Everard Park homestead (S.A.); 5.ix.1957; Fl.; CANB - H.B.Williamson s.n. CANB 190325: Piangil (Vic.); ix.1924; Fr.; CANB - W.Zimmer s.n. CANB 190324: Mildura (Vic.).

Material examined anatomically: Keighery 216; Forde 912; Royce 5476; Beauglehole 13165; Alford 576; Welsted s.n. PERTH 00317632; Myson s.n. PERTH 00316644;.

Classification. Triticodae; Bromeae.

Cite this publication as:
C.M. Weiller, M.J. Henwood, J. Lenz and L. Watson (1995 onwards). `Pooideae (Poaceae) in Australia - Descriptions and Illustrations'. URL http://muse.bio.cornell.edu/delta/
Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993) should also be cited.

References and Acknowledgements