The grass genera of the world
~ Panicum section Bulbosa, but cf. Urochloa
Type species: Z. bulbosa (Kunth) Bess.
Habit, vegetative morphology. Perennial; rhizomatous, or caespitose. The flowering culms leafy. Culms 60–150 cm high; herbaceous; tuberous; 3–8 noded. Culm nodes glabrous. Culm leaves present (20–50 cm long). Culm leaf sheaths keeled, or compressed, or rounded. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Leaf blades linear; broad to narrow; 4–15 mm wide; flat; persistent. Ligule present; an unfringed membrane, or a fringed membrane (?); truncate; 0.6–1.2 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality; hermaphrodite.
Inflorescence. Inflorescence 12–40 cm long, of spicate main branches, or paniculate (?); contracted (the primary branches appressed to the main axis); non-digitate. Inflorescence with axes ending in spikelets. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelets solitary; pedicellate (the pedicels 0.3–2 mm long). Pedicel apices glabrous, concave, cupuliform. Spikelets overlapping or not.
Female-fertile spikelets. Spikelets 3–3.5 mm long; elliptic; compressed laterally to not noticeably compressed; falling with the glumes. The upper floret not stipitate. Rachilla terminated by a female-fertile floret. Hairy callus absent.
Glumes two; very unequal; (the upper) about equalling the spikelets; long relative to the adjacent lemmas; hairless; membranous, glabrous; pointed to not pointed; muticous, or the second mucronate, awnless; non-carinate; very dissimilar to similar. Lower glume 0.5–0.7 times the length of the upper glume; 3 nerved. Upper glume 5 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 muticous or mucronate, awnless.
Female-fertile florets 1. Lemmas elliptic; decidedly firmer than the glumes; striate to rugose (uniformly striate, or finely transversely rugose); becoming indurated; yellow in fruit, or brown in fruit; entire; pointed; acute, awnless; hairless; dorsally rounded, non-carinate; having the margins inrolled against the palea. Palea present; relatively long; tightly clasped by the lemma.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4. The anatomical organization conventional. Biochemical type NADPME; XyMS. PCR sheath outlines uneven. PCR sheath extensions absent. PCR cell chloroplasts centrifugal/peripheral. Mesophyll not Isachne-type; without circular cells; not traversed by colourless columns; without arm cells; without fusoids. The lamina symmetrical on either side of the midrib.
Cytology. 2n = 16, 54, and 72 (plus aneuploids).
Classification. Watson & Dallwitz (1994): not described separately. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Cenchrinae. 1 species (Z. bulbosa, = Panicum bulbosum).
Distribution, phytogeography, ecology. Southern U.S.A. to Ecuador, South Africa, Australia.
Seemingly commonly adventive. Mesophytic. In Australia in temperate wet sclerophyll forests, temperate sub-humid woodlands and semi-aid shrub woodlands.
Economic aspects. Important native pasture species: Z. bulbosa.
References, etc. Morphological/taxonomic: Webster (1987).
Special comments. Our slides of Panicum bulbosum leaf epidermis to be examined?. Fruit data wanting. Anatomical data for ts only. Illustrations. • Z. bulbosum: as Panicum, Hitchcock and Chase (1950)
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classifications. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., Macfarlane, T.D., and Dallwitz, M.J. 1992 onwards. The 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. Version: 13th November 2017. delta-intkey.com/grass’.