Pseudochaetochloa A. Hitchc.
From the Greek pseudos (false) and chloa (a grass), with reference to Chaetochloa (a synonym of the grass genus Setaria).
Sometimes referred to Pennisetum
Habit, vegetative morphology. Perennial; caespitose. Culms 50–150 cm high; herbaceous; branched above. Culm nodes hairy (usually), or glabrous. Culm internodes solid. Leaves non-auriculate. Leaf blades narrow; 2–5 mm wide; without cross venation; persistent; a fringe of hairs.
Reproductive organization. Plants dioecious (seemingly - only male material as yet formally described); without hermaphrodite florets. The spikelets all alike in sexuality (on the male plants, at least); female-only, or male-only. Plants outbreeding.
Inflorescence. Inflorescence paniculate; contracted (the spikelets in clusters of 1–5, with reduced-branch bristles); spicate. Primary inflorescence branches inserted all around the main axis. Inflorescence axes not ending in spikelets. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets with ‘involucres’ of ‘bristles’. The ‘bristles’ relatively slender, not spiny; deciduous with the spikelets. Spikelets not secund; pedicellate. Pedicel apices discoid.
Female-sterile spikelets. Male spikelets about 6 mm long, not compressed, falling with the glumes. Rachilla not prolonged. Glumes 2, unequal, membranous, much shorter than the adjacent lemmas, 3-nerved. Two male florets per spikelet, the lemmas 5-nerved. Palea conventionally eu-panicoid, 2-nerved. Lodicules 2, fleshy. Rachilla of male spikelets terminated by a male floret. The male spikelets with glumes; without proximal incomplete florets; 2 floreted. The lemmas awnless. Male florets 2.
Female-fertile spikelets. Spikelets as yet not formally described - only male plants known.
Spikelets with proximal incomplete florets (presumably).
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally (quite thick walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; (72–)75–78 microns long; 6–7.5 microns wide at the septum. Microhair total length/width at septum 10.12. Microhair apical cells (37.5–)39–40.5(–42) microns long. Microhair apical cell/total length ratio 0.52–0.56. Stomata common; 36–42 microns long. Subsidiaries triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. Prickles abundant. Costal short-cells conspicuously in long rows. Costal silica bodies horizontally-elongated crenate/sinuous, or ‘panicoid-type’; not sharp-pointed.
Transverse section of leaf blade, physiology. C4; XyMS–. PCR sheath outlines uneven. PCR sheath extensions present. Maximum number of extension cells 1. Mesophyll with radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs, or ‘nodular’ in section; with the ribs very irregular in sizes. Midrib conspicuous; having a conventional arc of bundles; with colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present, or absent; nowhere forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Taxonomy. Panicoideae; Panicodae; Paniceae.
Distribution, ecology, phytogeography. 1 species; Australia. Species of open habitats. Stony slopes.
Australian. North and East Australian. Tropical North and East Australian.
References, etc. Leaf anatomical: this project.
Special comments. Only male plants have yet been formally described inder this genus. It is now established that Pennisetum arnhemicum F. Muell. is the male component (Lazarides and Macfarlane, pers. comm.), but full details and the revised generic circumscription are not yet formally published. Fruit data wanting.
Illustrations. • General aspect, spikelets. • Male inflorescence, spikelet. • Male spikelet details. • Female inflorescence and spikelets. • Female spikelet details. • Abaxial epidermis of leaf blade
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).
