Grass Genera of the World

L. Watson and M. J. Dallwitz


Australopyrum (Tsvelev) A. Löve

Sometimes referred to Agropyron; cf.Brachypodium

Habit, vegetative morphology. Perennial; caespitose. Culms 17–60 cm high; herbaceous; unbranched above. Young shoots extravaginal (A. calcis), or intravaginal. Leaves not basally aggregated; auriculate. Sheath margins free. Leaf blades narrow; rolled (usually), or flat; without cross venation; persistent; an unfringed membrane; truncate; short.

Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets; inbreeding; exposed-cleistogamous, or chasmogamous, or exposed-cleistogamous and chasmogamous.

Inflorescence. Inflorescence few spikeleted to many spikeleted; a single raceme (the spikelets somewhat spreading). Inflorescence with axes ending in spikelets (these often abortive), or axes not ending in spikelets (terminated by a straight or curled, bristlelike appendage in A. uncinatum). Rachides hollowed (notched against the spikelets). Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; distichous; subsessile to pedicellate (i.e., the spikelets more or less distinctly stalked); imbricate.

Female-fertile spikelets. Spikelets 6–14 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets.

Glumes present; two; very unequal to more or less equal; shorter than the spikelets; joined (slightly, at the base); lateral to the rachis; hairy (A. calcis), or hairless; when hairless, glabrous; pointed; not subulate; awnless; non-carinate; similar (rigid, broadly lanceolate, rather asymmetric). Lower glume 4–6 nerved. Upper glume (3–)5–7 nerved (sic: glumes not ‘3 nerved’). Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.

Female-fertile florets 5–7. Lemmas slightly involute; similar in texture to the glumes; not becoming indurated; entire; pointed; awned. Awns 1; median; apical; hooked (in A. uncinatum), or not hooked; non-geniculate; much shorter than the body of the lemma to about as long as the body of the lemma. Lemmas carinate to non-carinate; without a germination flap; 5 nerved, or 7 nerved, or 10–14 nerved (A. uncinatum); with the nerves confluent towards the tip. Palea present; relatively long; apically notched; awnless, without apical setae; 2-nerved; 2-keeled. Lodicules present; 2; ciliate, or glabrous. Stamens 3. Anthers 2–4 mm long (sic); not penicillate. Ovary apically hairy. Styles free to their bases. Stigmas 2; white.

Fruit, embryo and seedling. Fruit adhering to lemma and/or palea, or free from both lemma and palea; small (3–4 mm long); not grooved. Hilum long-linear. Embryo small.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally (the costals smaller); of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular (a few almost fusiform in A. pectinatum); having markedly sinuous walls (exaggeratedly so in A. velutinum). Microhairs absent. Stomata common; 33–39 microns long (in A. retrofractum and A. velutinum), or 40.5–42 microns long (in A. pectinatum). Subsidiaries parallel-sided, or parallel-sided and dome-shaped, or parallel-sided, dome-shaped, and triangular (in A. velutinum); including both triangular and parallel-sided forms on the same leaf (and domes, in A. velutinum), or not including both parallel-sided and triangular forms on the same leaf. Guard-cells overlapped by the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Prickles and macrohairs often common. Crown cells present, or absent. Costal short-cells predominantly paired. Costal silica bodies rounded (plus many irregularly isodiametric forms).

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade; traversed by columns of colourless mesophyll cells. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size (round topped). Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups to not present in discrete, regular adaxial groups (scarcely developed bulliform groups only, in some of the furrows); in groups of fairly evenly sized cells. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles); forming ‘figures’ (most bundles with I’s). Sclerenchyma all associated with vascular bundles.

Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid. Haplomic genome content W.

Taxonomy. Pooideae; Triticodae; Triticeae.

Distribution, ecology, phytogeography. 5 species; Australia, New Zealand and New Guinea.

Paleotropical and Australian. Indomalesian. Papuan. North and East Australian. Temperate and South-Eastern Australian.

References, etc. Morphological/taxonomic: Löve 1984. Leaf anatomical: this project.

Illustrations. • Spikelet. • Floret


Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘Grass Genera of the World: Descriptions, Illustrations, Identification, and Information Retrieval; including Synonyms, Morphology, Anatomy, Physiology, Phytochemistry, Cytology, Classification, Pathogens, World and Local Distribution, and References.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).

Index