Heteranthelium Hochst.
From the Greek heteros (different) and anthele (a ‘floret’ of a reed), alluding to an inflorescence comprising fertile and sterile/modified spikelets.
Habit, vegetative morphology. Annual. Culms 5–30 cm high; herbaceous. Culm nodes with short bristles below the nodes. Leaves auriculate. Sheath margins joined, or free. Leaf blades narrow; flat; without cross venation; an unfringed membrane; truncate; 0.2–0.8 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; hermaphrodite and sterile (each spikelet cluster with the lowest one or two members fertile, the other sterile).
Inflorescence. Inflorescence a false spike, with spikelets on contracted axes (in clusters); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes disarticulating; falling entire (i.e., the clusters falling). Spikelets unaccompanied by bractiform involucres, not associated with setiform vestigial branches; in clusters of 1–2 fertile and 1–3 sterile; not secund; distichous.
Female-fertile spikelets. Spikelets 8–15 mm long; compressed laterally; falling with the glumes (i.e., in the clusters); not disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; somewhat spinulose; the rachilla extension with incomplete florets. Callus very short.
Glumes two; relatively large; displaced (side by side away from the rachis); subulate; awned (both awn-like); similar (thinly leathery, linear-subulate, with basal capitate hairs). Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets 1–3; clearly specialised and modified in form (forming a tuft of awns). Spikelets without proximal incomplete florets.
Female-fertile florets 1–2 (usually the first two). Lemmas modified into the awn; decidedly firmer than the glumes (cartilaginous to leathery); entire; pointed; awned. Awns 1; median; apical; non-geniculate; much shorter than the body of the lemma; entered by several veins. Lemmas hairy (tuberculate on the back, with capitate hairs on the margins); non-carinate; without a germination flap; 5–7 nerved. Palea present; relatively long; apically notched; with apical setae (apical cusps, about 1 mm long); 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; ciliate; not toothed; not or scarcely vascularized. Stamens 3. Anthers 0.8–1.2 mm long. Ovary hairy. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit somewhat adhering to lemma and/or palea; medium sized (4.5–7.5 mm long); ellipsoid; longitudinally grooved; compressed laterally; with hairs confined to a terminal tuft. Hilum long-linear. Embryo large to small (up to 1/3 the caryopsis length). Endosperm hard; without lipid; containing only simple starch grains. Embryo with an epiblast.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (costal ‘long-cells’ often short). Mid-intercostal long-cells mostly rectangular; having straight or only gently undulating walls. Microhairs absent. Stomata common; 39–45 microns long. Subsidiaries parallel-sided, or parallel-sided and dome-shaped. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare. Abundant macrohairs present. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous, or horizontally-elongated smooth, or rounded (few).
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll without adaxial palisade. Midrib not readily distinguishable; with one bundle only. The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups (in the furrows); in simple fans. All the vascular bundles accompanied by sclerenchyma (but the smallest with minute strands only). Combined sclerenchyma girders present; forming ‘figures’ (I’s and anchors). Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid. Haplomic genome content Q.
Taxonomy. Pooideae; Triticodae; Triticeae.
Distribution, ecology, phytogeography. 1 species; southwest Asia. Xerophytic; species of open habitats. On dry slopes.
Holarctic. Tethyan. Irano-Turanian.
Rusts and smuts. Rusts — Puccinia. Taxonomically wide-ranging species: Puccinia graminis and Puccinia striiformis.
References, etc. Morphological/taxonomic: Löve 1984. Leaf anatomical: Metcalfe 1960; this project.
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).