Anisopogon R.Br.
From the Greek anisos (unequal) and pogon (beard), referring to the hair on the lemma backs.
Habit, vegetative morphology. Oat-like perennial; caespitose. Culms 60–110 cm high; herbaceous. Culm nodes glabrous. Culm internodes hollow. Leaves mostly basal; non-auriculate. Leaf blades linear-lanceolate; narrow; 2–3 mm wide; flat to rolled; without cross venation; persistent; a fringed membrane (the membrane short to relatively long, hairy on the back). Contra-ligule absent.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence few spikeleted (the spikelets large); paniculate; open; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 40–60 mm long; compressed laterally; disarticulating above the glumes. Rachilla usually prolonged beyond the uppermost female-fertile floret (the slender prolongation 6–8 mm long, in the palea groove), or terminated by a female-fertile floret; the rachilla extension (when present) with incomplete florets. Hairy callus present. The callus hairs white (dense). Callus long (about 6 mm long); pointed.
Glumes two; relatively large; more or less equal (the upper slightly longer); exceeding the spikelets; long relative to the adjacent lemmas; pointed (lanceolate, attenuate); awnless; non-carinate; similar (3–5 cm long, rather flat and leafy). Lower glume 7–9 nerved. Upper glume 7–9 nerved. Spikelets with female-fertile florets only, or with incomplete florets (usually with a single, abortive floret). The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped (minute). Spikelets without proximal incomplete florets.
Female-fertile florets 1. Lemmas decidedly firmer than the glumes; not becoming indurated (but very firmly leathery); incised; 3 lobed; awned. Awns 3; median and lateral; the median different in form from the laterals; from a sinus; geniculate; hairless to hairy; much longer than the body of the lemma (up to 8 cm long); entered by several veins (5); persistent. The lateral awns shorter than the median (15–25 mm long, straight to twisted but non-geniculate, relatively slender). Lemmas hairy (with dense, white hairs); non-carinate (rounded on the back); without a germination flap; 3 nerved. Palea present; relatively long; not prow-tipped; apically notched; awnless, without apical setae; textured like the lemma; firm, except for the membranous, bifid tip; 2-nerved; 2-keeled (the keels closely apposed below, diverging towards the tip). Palea keels wingless. Lodicules present; 3; free; membranous (two ‘stipoid’ and larger, the third smaller and flimsier); glabrous; not toothed; not or scarcely vascularized. Stamens 3. Anthers 10–14 mm long; not penicillate; without an apically prolonged connective. Ovary hairy (sparingly so, towards the apex). Styles free to their bases. Stigmas 2, or 3; white.
Fruit, embryo and seedling. Fruit medium sized; not noticeably compressed. Hilum long-linear. Pericarp free, or loosely adherent. Embryo small; waisted. Endosperm containing compound starch grains.
Ovule, embryology. Micropyle oblique. Outer integument covering no more than the chalazal half of the ovule; more than two cells thick at the micropylar margin. Inner integument continuous, the micropyle constricted; thickened around the micropyle. Synergids not haustorial; without large, globular starch grains.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally (or the costals narrower); of similar wall thickness costally and intercostally (or the costals somewhat thicker-walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls and having straight or only gently undulating walls (conspicuously pitted). Microhairs absent. Stomata absent or very rare; 18–27 microns long. Guard-cells overlapping to flush with the interstomatals (i.e., in the few seen). Intercostal short-cells common; in cork/silica-cell pairs. Heavily pitted prickle bases abundant. Crown cells absent. Costal short-cells varying in arrangement from file to file, conspicuously in long rows, or predominantly paired, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies ‘panicoid-type’ (mostly), or tall-and-narrow (a few); predominantly short dumb-bell shaped.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs; with the ribs very irregular in sizes (small, round-topped ribs alternating with large, flat-topped ones). Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (one group in each furrow); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’ (most bundles with a conspicuous ‘I’). Sclerenchyma not all bundle-associated. The ‘extra’ sclerenchyma in abaxial groups, or in a continuous abaxial layer.
Taxonomy. Stipoideae; Anisopogoneae.
Distribution, ecology, phytogeography. 1 species; Australia. Xerophytic; species of open habitats; glycophytic. Light Eucalyptus forest and heathland.
Australian. North and East Australian. Temperate and South-Eastern Australian.
References, etc. Leaf anatomical: this project.
Special comments. An isolated monotypic, seeming nearest to Stipeae; but the taxonomic relationships of Anisopogon have yet to be convincingly determined, despite the broad scope and good quality of the available descriptive data. A prime candidate for comparative DNA studies.
Illustrations. • Ligule. Anisopogon avenaceus. • Flower. Anisopogon avenaceus. Showing lodicules. • Spikelet. Anisopogon avenaceus. Showing rachilla prolongation.
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).
