Amphibromus nervosus (Hook.f.) Baill., Hist. Pl. 12: 203 (1893).

Avena nervosa R.Br., Prodr. 1: 178 (1810), nom. illeg., non Lam. (1791); Danthonia nervosa Hook.f., Fl. Tasmania 2: 121, pl. 163A (1858); Avenastrum nervosum Vierh., Verh. Ges. Deutsch. Naturf. 1: 672 (1913); Amphibromus nervosus (Hook.f.) Druce, Bot. Soc. Exch. Club Brit. Isl. 1916: 604 (1917), nom. superfl. T: Iter Austral., 1802-5, R.Brown; lecto: BM (sheet no. 6222)

Illustrated in: Fl. N.S.W. 4: 597 (spikelet and floret).

Vegetative form. Perennial, erect, caespitose (occasionally rooting at the nodes). Culms to 125 cm high, 2-5 noded. Mid-culm nodes glabrous, exposed, constricted. Mid-culm internodes hollow, glabrous or scabrous (slightly), terete to compressed. Leaves non-auriculate. Basal leaf sheaths not keeled, terete, glabrous, with the veins equally striate. Ligule 10-20 mm long, membranous, acute, entire (becoming lacerated with age). Leaf blades flat to involute, linear, to 300 mm long, 1.5-3.5 mm wide; adaxially scabrous, channelled; abaxially glabrous to abaxially scabrous, with the veins equally striate (?).

Reproductive organization. Plants bisexual. Incomplete spikelets absent. Inflorescence of cleistogamous spikelets, or chasmogamous spikelets (with cleistogamous and/or chasmogamous florets).

Inflorescence. Inflorescence a panicle, erect, contracted, symmetrical, partially exserted. Rachides to 400 mm long, terete (becoming angled towards the apex), glabrous (becoming scabrous towards the apex). Primary inflorescence branches paired or clustered, appressed (to 15 cm long). Spikelets erect, spreading.

Hermaphrodite (`perfect') spikelets. Hermaphrodite spikelets pedicellate, 10-16 mm long, laterally compressed, not disarticulating as a separate unit, disarticulating above the glumes. Pedicels to 20 mm long, erect, scabrous. Glumes two per spikelet, dissimilar (the upper longer and broader), subequal to unequal in length, shorter than the florets, approximately half the proximal lemma in length (?). Lower glume c. 2/3s the length of the upper glume (?), ovate, (2.6-)3.4-5(-5.5) mm long, 0.9-1.7 mm wide, weakly keeled, acute, muticous; 1-3(-5) veined; intercostal regions glabrous. Upper glume ovate, (3.1-)4.5-6.2(-6.7) mm long, (1-)1.5-2.3 mm wide, weakly keeled, acute, muticous; 3-5 veined; intercostal regions glabrous. Rudimentary florets distal to the hermaphrodite florets (?). Incomplete florets absent (?). Hermaphrodite florets 4-6 per spikelet (cleistogamous and/or chasmogamous). Rachilla disarticulating between the florets, disarticulating directly below the florets, segments bearded at the apex, apically prolonged; terminated by a rudimentary floret (?). Callus present, blunt, hirsute (?). Lemma laterally compressed, 5-7.2 mm long, not keeled, bidentate or dentate (occasionally, more often 2-toothed with 2 smaller lateral teeth or notches, inner teeth (0.25-)0.3-0.65(-1.05) mm long), 2 -lobed or 4 -lobed, awned. Lemma (5-)7 veined. Lemma veins not confluent apically; intercostal regions scabrous. Awns 1, median. Median awn much longer than the body of the lemmas, 12-22 mm long, 1 veined, dorsal, arising from the upper half of the lemma or from the mid-point of the lemma or from the lower half of the lemma (usually from upper half, occasionally about 2/3s of the lemma length from the tip), geniculate, column twisted, scabrous (pale, rarely to dark purple-brown). Palea fully developed, 2/3s the length of the lemma to slightly shorter than the lemmas (75-95% the length of the lemma), 2-keeled, acute; 2 veined, veins ciliate; intercostal regions glabrous to intercostal regions papillose. Lodicules 2, hyaline, acute, glabrous. Stamens 3. Anthers 2.2-3 mm long. Cleistogamous anthers 0.28-1.4 mm long.

Fruit. Fruit free from both lemma and palea, oblong, dorsiventrally compressed (dorsally), 1.36-2.15 mm long, glabrous. Hilum 25-50% the length of the fruit, linear (reddish-brown). Embryo 16-30(-40)% the length of the caryopsis.

Distribution. Endemic. New South Wales, Australian Capital Territory, Victoria, Western Australia, and South Australia.

Ecology. On the floodplains and banks of inland rivers of southern mainland Australia. Flowers in response to rain or flooding.

Classification. Pooideae; Poodae; Aveneae.

Closely resembling A. neesii, but distinguished by the awn, which arises from lower on the back of the lemma, the usually more scabrous lemma and the broader lemma apex.

References. Morphology: Jacobs & Lapinpuro 721 (1986). Taxonomy: Jacobs & Lapinpuro 720-721 (1986); Jacobs 599 (1990). Illustrations: amphib01.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