Grass Genera of the World

L. Watson and M. J. Dallwitz


Scrotochloa Judziewicz

From the Latin scroto (pouch) and chloa (grass), in reference to the pouch- or urn-shaped female spikelets.

Sometimes referred to Leptaspis

Habit, vegetative morphology. Perennial; decumbent. Culms 30–100 cm high; herbaceous; unbranched above. Culm nodes glabrous. Culm internodes solid to hollow. Leaves not basally aggregated; non-auriculate; without auricular setae. Leaf blades broad; 10–70 mm wide; pseudopetiolate (becoming inverted by twisting of the ‘petiole’); pinnately veined (the laterals diverging obliquely from the midrib); cross veined; persistent; rolled in bud; ligule present; an unfringed membrane (minute). Contra-ligule absent.

Reproductive organization. Plants monoecious with all the fertile spikelets unisexual; without hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; female-only and male-only. The male and female-fertile spikelets mixed in the inflorescence. The spikelets overtly heteromorphic.

Inflorescence. Inflorescence paniculate (1-noded); open; non-digitate. Primary inflorescence branches 4–8. Inflorescence espatheate (the spikelet branchlets without subtending bracts); not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes disarticulating; falling entire (the inflorescence separating below the single node). Spikelets paired; pedicellate (the female pedicels clavate); not in distinct ‘long-and-short’ combinations (the female spikelets tending to be accompanied by pedicelled males, the pedicels of similar length).

Female-sterile spikelets. The male spikelets much smaller, stamens 6, anthers non-penicillate, lodicules absent, the floret caducous. The male spikelets with glumes; 1 floreted. Male florets 6 staminate.

Female-fertile spikelets. Spikelets 4–9 mm long; compressed laterally; falling with the glumes. Rachilla terminated by a female-fertile floret; hairless. Hairy callus absent.

Glumes two; relatively large; more or less equal; long relative to the adjacent lemmas; pointed (acute); awnless; very dissimilar (both ovate, caducous, purplish brown). Lower glume 5–7 nerved. Upper glume 5–7 nerved. Spikelets with female-fertile florets only.

Female-fertile florets 1. Lemmas urceolate-scrotoform, with connate margins and a terminal pore through which the style emerges; decidedly firmer than the glumes; becoming indurated; awnless; densely hairy (uncinate-pubescent); non-carinate; 9 nerved. Palea present (linear); relatively long; awnless, without apical setae; indurated; 2-nerved; 2-keeled. Lodicules absent. Stamens 0 (with 6 minute staminodes). Styles fused (into one). Stigmas 3.

Fruit, embryo and seedling. Fruit free from both lemma and palea.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous (the zones conspicuously sinuous, in the material seen). Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals much narrower - reminiscent of epidermal fibres). Intercostal zones exhibiting many atypical long-cells (in the sense that they are very variable in width, and of divers shapes). Mid-intercostal long-cells often rectangular (but frequently with one or both ends oblique or irregular); having markedly sinuous walls. Microhairs absent. Stomata absent or very rare (in places), or common. Subsidiaries mostly low to high dome-shaped (frequently accompanied by small interstomatal or long-cells almost constituting additional subsidiaries), or parallel-sided. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies rounded to upright-ovoid, with a raised prickly belt around the equator (small, abundant, the form as yet unknown elsewhere); sharp-pointed (i.e. around the middle).

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll without arm cells; with fusoids. Midrib conspicuous; with colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups; in simple fans (these wide).

Special diagnostic feature. Having female spikelets, with shell- or urn-shaped lemmas which are closed save for an apical pore.

Taxonomy. Bambusoideae; Oryzodae; Phareae.

Distribution, ecology, phytogeography. 2 species; Ceylon and Southeast Asia to New Guinea, Australia and the Solomon Islands. Shade species. In forest.

Paleotropical and Australian. Indomalesian. Indian, Indo-Chinese, Malesian, and Papuan. North and East Australian. Tropical North and East Australian.

References, etc. Morphological/taxonomic: Judziewicz 1984. Leaf anatomical: this project.

Special comments. Fruit data wanting.


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).

Index