The grass genera of the world
Habit, vegetative morphology. Perennial. The flowering culms leafy. Culms reaching 40–60 m long; woody and persistent (but weak); scandent (on trees and shrubs); branched above. Rhizomes pachymorph. Leaves not basally aggregated. Leaf blades linear-lanceolate to lanceolate; narrow; 7–9 mm wide (to 15 cm long); not cordate, not sagittate (abruptly attenuate); (presumably) pseudopetiolate; disarticulating from the sheaths (presumably). Ligule present (oblong).
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence a fascicle of single, bracteate spikelets, pendulous, subspiciform, recalling...(that)...of Coix by its ventricose lemmas; spatheate; a complex of partial inflorescences and intervening foliar organs.
Female-fertile spikelets. Spikelets 15–16 mm long; not noticeably compressed (? ventricose); falling with the glumes. Rachilla prolonged beyond the uppermost female-fertile floret.
Glumes two to several (2–3, membranous); pointed (acuminate or cuspidate); awnless; similar. Lower glume many nerved. Upper glume many nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1, or 2 (their lemmas cuspidate, glabrous, shining, becoming ventricose). The proximal lemmas many-nerved; exceeded by the female-fertile lemmas; becoming indurated.
Female-fertile florets 1. Lemmas glossy; becoming saccate (ventricose); decidedly firmer than the glumes; becoming indurated; entire; pointed; awned (long-cuspidate). Awns 1; median; apical; non-geniculate. Lemmas hairless; non-carinate; many-nerved. Palea present; relatively long; awnless, without apical setae; indurated (and inflated); parinervia; 2-keeled (?- dorsally sulcate). Lodicules present (large); 3; free. Stamens 6. Ovary apically hairy; with a conspicuous apical appendage. The appendage broadly conical, fleshy. Stigmas 3.
Fruit, embryo and seedling. Pericarp fleshy (apically rostrate); free.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous (mainly because of the macrohairs and prickles). Papillae present; costal and intercostal. Intercostal papillae over-arching the stomata (mostly with four papillae over-arching each stomatal apparatus); several per cell (mostly 5–8 in a median longitudinal row, large, circular, thickened). Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; elongated; clearly two-celled; panicoid-type; 60–72 microns long; 4.2–6 microns wide at the septum. Microhair total length/width at septum 10–16.4. Microhair apical cells 28.5–39 microns long. Microhair apical cell/total length ratio 0.48–0.54. Stomata common; 18–21 microns long. Subsidiaries non-papillate. The costal zones with large, bulbous-based macrohairs and occasional prickles. Costal short-cells predominantly paired (but in places the intervening long-cells are quite short). Costal silica bodies saddle shaped (predominating), or oryzoid (a few, intergrading with saddles); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; with adaxial palisade; with arm cells; with fusoids. The fusoids external to the PBS. Leaf blade adaxially flat (except for the midrib). Midrib conspicuous; with one bundle only. The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups (between the laterally adjacent pairs of fusoids); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles); forming figures (most bundles with anchors). Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Bambusodae; Bambuseae; Hickeliinae. 1 species (P. perrieri).
Distribution, phytogeography, ecology. Madagascar.
References, etc. Leaf anatomical: studied by us.
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: 11th December 2017. delta-intkey.com/grass’.