Bromus hordeaceus L. subsp. hordeaceus

Sp. Pl. 77 (1753).

T: see Matthei, O (1986) El Genero Bromus (Poaceae) in Chile. for types.
Bromus mollis L., Sp. Pl. ed. 2, 1: 112 (1762). T: see Matthei, O (1986) El Genero Bromus (Poaceae) in Chile. for types

Vegetative form. Annual (or sometimes biennial (Tutin 1980)). Leaves scattered along the culms. Culms 21-108 cm high, 2-3 noded. Mid-culm nodes hairy (pilose). Mid-culm internodes hollow, commonly glabrous or puberulous (minutely), terete. Leaves non-auriculate. Basal leaf sheaths not keeled, terete, puberulous to pilose, with margins connate, in lower 2/3s, hyaline (the free portions only), ciliolate or ciliate. Ligule (0.75-)1.5-3 mm long, hyaline, smooth, acute to obtuse, erose to lacerate, abaxially glabrous or hairy (puberulous). Leaf blades flat, linear, (45-)70-220 mm long, (2-)3-7 mm wide; adaxially pilose; abaxially puberulous to abaxially pilose; with margins ciliolate, apices acuminose.

Reproductive organization. Plants bisexual. Incomplete spikelets absent. Inflorescence of cleistogamous spikelets (although some florets have terminally exserted anthers).

Inflorescence. Inflorescence a raceme to a panicle, contracted, oblong. Main inflorescence axis 115-470 mm long. Peduncles 105-455 mm long, glabrous or puberulous (the trichomes retrorse and sometimes restricted to a narrow acropetal zone). Rachides (15-)25-110 mm long, subterete, scabrous to puberulous. Rachis angles scabrous to puberulous. Primary inflorescence branches spreading, verticillate, with spikelets inserted at the base. Spikelets 2-3 on a typical ultimate inflorescence branch, on first order branches, spreading.

Hermaphrodite (`perfect') spikelets. Hermaphrodite spikelets pedicellate, 12-20 mm long, very slightly laterally compressed or dorsally compressed to not noticeably compressed, oblong or ovate, disarticulating as a separate unit, disarticulating above the glumes. Pedicels 1.25-11.5(-16.5) mm long. Glumes two per spikelet, free, similar, subequal. Lower glume c. 3/4s the length of the upper glume, narrowly ovate to narrowly elliptic, 6-7.5 mm long, 1.5 mm wide, chartaceous, acropetally keeled or dorsally rounded, acuminate to acute, muticous, margin hyaline, margin smooth; 5 veined, veins obscure, midvein puberulous to midvein pilose; intercostal regions puberulous. Upper glume narrowly elliptic, 7.5-9 mm long, 1.5-2 mm wide, chartaceous, dorsally rounded, acuminate to acute, muticous, margin hyaline to margin membranous (0.75 mm wide), margin smooth; 7-9 veined, veins obscure, midvein puberulous; intercostal regions puberulous. Incomplete florets present, distal to the hermaphrodite florets. Hermaphrodite florets 8-10 per spikelet. Rachilla disarticulating between the florets, disarticulating directly below the florets, flexuous (internodes unequally expanded acropetally), scabrous to puberulous, elongated between all florets, apically prolonged. Callus present, blunt, 0.25-0.5 mm long, glabrous. Lemma similar in firmness to the glumes, narrowly obovate, 8-9.5 mm long, 2.5-3 mm wide, chartaceous, not keeled, acuminate to rounded, entire or erose (shallowly), 0 -lobed or 2 -lobed, awned. Lemma margins ciliolate. Lemma 7-9 veined (the 2 either side of the central vein may be obscure). Lemma veins confluent towards the apex, obscure, not connected by transverse veins or connected by obscure transverse veins, pilose, with the hairs on all the veins, with the hairs extending the length of the veins (although sometimes more obvious acropetally); intercostal regions puberulous, the hairs over the entire dorsal surface (although sometimes more obvious acroptelly). Awns 1, median. Median awn about as long as the body of the lemmas, 4-9 mm long, 3 veined (only 1 is obvious), subapical, straight or curved, column not twisted or column twisted (but slightly), scabrous. Palea fully developed, equalling the lemmas, thinner than the lemmas, tightly clasped by the lemmas, narrowly elliptic to narrowly obovate, 6.5-7 mm long, 1.5 mm wide, membranous, 2-keeled, keels wingless, obtuse to truncate, entire; 2 veined, sparsely veins pilose; intercostal regions glabrous, or intercostal regions puberulous (rarely). Lodicules 2, hyaline, acute to obtuse, with entire margins, glabrous. Stamens 3. Anthers 0.75-2.25 mm long, basally 2-lobed. Ovary pilose, with the hairs only at the apex. Styles 2, free to their bases. Distal incomplete florets (2-)3-4 per spikelet, neuter, awned, paleate or epaleate. Distal male florets with 1 stamens.

Fruit. Fruit adhering to lemma and adhering to palea (more so to the palea), elliptical, dorsiventrally compressed, 5.5-6 mm long, 1-2 mm wide, not grooved, pilose, with dense hairs. Hilum 4.5-5 mm long.

Abaxial leaf blade epidermis. Leaf anatomical data recorded.

Costal/intercostal zonation conspicuous; the intercostal zones bordering the midrib 20-37 cells wide; epidermis differentiated into long- and short-cells; long-cells similar in shape costally and intercostally, or 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; intercostal and marginal; antrorse and retrorse; variable in size and form, or 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 about as long as the width of an intercostal long-cell to 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; intercostal; intergraded with long prickles; unicellular; robust; with thickened walls; sparse but frequent; more than 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; hexagonal to inflated; long-cell walls straight; end walls vertical, or angled; the intercostal long-cell walls not conspicuously pitted. 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; when present, throughout the intercostal zones, or confined to the outer regions of the intercostal zones; solitary. Unsilicified intercostal short-cells square; walls straight. Intercostal silica bodies absent, or imperfectly developed; when present, horizontal-crenate and cuboid.

Stomata common; present in all the intercostal zones; distributed throughout the intercostal zones; arranged in definite rows. Stomatal rows in the widest intercostal zones 4-7; evenly dispersed. Stomata 51-58.5-60 m long; with guard-cells overlapped by the interstomatals. Subsidiaries dome-shaped to parallel-sided. The domes low, or of medium height.

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. Width of lamina across a primary vascular bundle 195-198 m. Lamina mid-zone in transverse section with ribs both adaxially and abaxially; the adaxial and abaxial ribs opposite one another. Adaxial furrows slight; wide. Adaxial furrows between the major vascular bundles only. Adaxial ribs more or less constant in size to irregular in size; round topped to flat-topped; opposite major vascular bundles only. Vascular bundles in the mid-lamina 20-22; 1 per rib. Abaxial furrows absent, or present between the vascular bundles. Abaxial ribs opposite major vascular bundles only; smaller than adaxial ribs.

Midrib pronounced in outline; adaxially raised and rounded; prominent abaxially. Midrib sclerenchyma present as massive girders both adaxially and abaxially. Midrib 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; 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 absent as discrete groups but the epidermis extensively bulliform. Abaxial epidermis of bulliform-like epidermal cells. Abaxial epidermal cell walls not thickened, or thickened. The cells often large and irregular in shape, or regular in shape, ovoid (rarely).

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 (which may be massive); the abaxial sclerenchyma forming girders; the combined girders forming I's. Outlines of lower order vascular bundles more or less circular. Lower order vascular bundles centrally situated; without adaxial sclerenchyma; without abaxial sclerenchyma; the smallest vascular bundles lacking sclerenchyma. The adaxial sclerenchyma of the mid-lamina all associated with vascular bundles.

Vouchers. Specimens examined morphologically: R.Pullen 2367: C.S.I.R.O., Black Mtn (A.C.T.); 18.xi.19609; Fl.; CANB - R.Pullen 8: Turner, Canberra (A.C.T.); 16.xii.1956; Fr.; CANB - L.Craven 2041: Camberwell (Vic.); 29.xi.1971; Fl., Fr.; Canb, CHR, K, L, LAE, MEL, US - J.Cullimore 123: 1 ml S. of Laverton (Vic.); 22.xi.1967; Fr.; CANB, MEL - R.Barker 171: Lower marshes, Jordan R. (Tas.); 9.xi.1964; Fl.; CANB - R.Barker 23: Hunting Grounds, Jordan R. (Tas.); 10.xi.1964; Fl.; CANB - M.Gray 3036: Uralla to Walcha, New England area (N.S.W.); xi. 1954; Fl.; CANB - I.B.Wilson 613: c. 116 km NE. of Nangwarry (S. A.); 24.x.1966; Fl., AD, CANB - D.E.Symon 4415: Mortlock experimental Stn. (S.A.); 9.xi.1966; Fr.; ADW, CANB - R.Story 6912: 8 mls SE. of Murrundi, Hunter Valley (N.S.W.); 25.xi.1959; Fr.; CANB - T.G.Hartley 13501: Lower W. slopes of Tinderry Mtn (N.S.W.); 28.xi.1971; Fl., CANB.

Material examined anatomically: R.Pullen 2367 ACT CANB; L.Craven 2041 Vic CANB; Wilson 613.

Classification. Triticodae; Bromeae.

References. Illustrations: bromus02.gif

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