Ichnanthus P. Beauv.
From the Greek chnos (a footstep or mark), perhaps referring to the appendages beneath the upper floret.
Including Ischnanthus Roem. & Schult., Navicularia Radd.
Habit, vegetative morphology. Annual, or perennial; caespitose, or decumbent. Culms herbaceous. Culm nodes hairy, or glabrous. Culm internodes solid, or hollow. The shoots not aromatic. Leaves not basally aggregated; non-auriculate. Leaf blades linear to ovate; broad, or narrow; pseudopetiolate, or not pseudopetiolate; cross veined, or without cross venation; persistent; short a fringed membrane, or a fringe of hairs.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate, or of spicate main branches (the primary branches sometimes unbranched); open; with capillary branchlets. Primary inflorescence branches inserted all around the main axis. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund. Pedicel apices truncate, or cupuliform.
Female-fertile spikelets. Spikelets 4–5 mm long; oblong, or elliptic, or lanceolate, or ovate, or obovate, or oblanceolate; adaxial (or not orientated); compressed laterally to compressed dorsiventrally (the L2 dorsally compressed); disarticulating above the glumes, or falling with the glumes; with distinctly elongated rachilla internodes between the florets. The upper floret conspicuously stipitate. The stipe beneath the upper floret not filiform; curved, not swollen (about 1 mm long, bearing a small, white, annular, membranous, minutely two-lobed appendage below the palea); homogeneous. Rachilla terminated by a female-fertile floret. Hairy callus absent.
Glumes two; very unequal (the lower usually about 1/2 to 3/4 of the spikelet length); (the longer) long relative to the adjacent lemmas; pointed; awnless; similar (membranous- herbaceous). Lower glume 0.5–0.75(–1) times the length of the upper glume; 3–7 nerved. Upper glume 5–9 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; paleate. Palea of the proximal incomplete florets fully developed. The proximal incomplete florets male. The proximal lemmas awnless; 5 nerved, or 7 nerved; decidedly exceeding the female-fertile lemmas; less firm than the female-fertile lemmas; not becoming indurated.
Female-fertile florets 1. Lemmas decidedly firmer than the glumes (papery to leathery); smooth; becoming indurated; white in fruit, or yellow in fruit; awnless; hairless (shiny); non-carinate; having the margins inrolled against the palea; with a clear germination flap; 5–7 nerved. Palea present; relatively long; tightly clasped by the lemma; entire; awnless, without apical setae; textured like the lemma; indurated; 2-nerved. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2; red pigmented.
Fruit, embryo and seedling. Disseminule often deciduous before the rest of the spikelet, comprising the fruit and the P2 on the stipe-like rachilla joint, enclosed by the L1. Fruit small; compressed dorsiventrally. Hilum short. Embryo large.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells rectangular; having markedly sinuous walls (these very thin). Microhairs present; panicoid-type; 88–92.7 microns long; 5.8–8.8 microns wide at the septum. Microhair total length/width at septum 10–15.4. Microhair apical cells 46.4–53.7 microns long. Microhair apical cell/total length ratio 0.53–0.58. Stomata common (in rows adjoining the veins); 51–70 microns long. Subsidiaries low dome-shaped and triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare (very few); not paired. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’; mostly dumb-bell shaped.
Transverse section of leaf blade, physiology. C3; XyMS+. Leaf blade ‘nodular’ in section. Midrib conspicuous (as a larger bundle and adaxial rib); with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (but most sclerenchyma in strands); forming ‘figures’ (few). Sclerenchyma all associated with vascular bundles.
Phytochemistry. Leaves containing flavonoid sulphates (1 species), or without flavonoid sulphates (1 species).
Special diagnostic feature. Plants not as in Dichanthelium (q.v.).
Cytology. 2n = 18, 20, 40, and 54.
Taxonomy. Panicoideae; Panicodae; Paniceae.
Distribution, ecology, phytogeography. 33 species; tropical America, Indomalayan region, Australia. Mesophytic; shade species and species of open habitats; glycophytic. Forest, grassland and disturbed ground.
Paleotropical, Neotropical, and Australian. African, Indomalesian, and Polynesian. Sudano-Angolan and West African Rainforest. Indian, Indo-Chinese, Malesian, and Papuan. Polynesian. Caribbean, Venezuela and Surinam, Amazon, Central Brazilian, Pampas, and Andean. North and East Australian. Sahelo-Sudanian. Tropical North and East Australian.
Rusts and smuts. Rusts — Puccinia. Taxonomically wide-ranging species: Puccinia levis.
References, etc. Leaf anatomical: this project.
Illustrations. • Palea and floret base. • 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).
