| # The grass genera of the world |

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

### Scrotochloa Judziewicz

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

~ Leptaspis

Type species: Type: S. urceolata (Roxb.) Judz.

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; without proximal incomplete florets.

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.

Classification. Watson & Dallwitz (1994): Bambusoideae; Oryzodae; Phareae. Soreng et al. (2015): Pharoideae; Phareae. 2 species.

Distribution, phytogeography, ecology. Ceylon and Southeast Asia to New Guinea, Australia and the Solomon Islands.

Shade species. In forest.

References, etc. Morphological/taxonomic: Judziewicz 1984. Leaf anatomical: studied by us - S. urceolata (Roxb.) Judziewicz.

Special comments. Fruit data wanting.

Illustrations. • Scrotochloa urceolata, morphology: Soderstrom et al., Smithsonian Contr. Bot. 65 (1987). • Scrotochloa urceolata, spikelet details: Soderstrom et al., Smithsonian Contr. Bot. 65 (1987). • Scrotochloa urceolata, leaf anatomy: Soderstrom et al., Smithsonian Contr. Bot. 65 (1987). • Scrotochloa urceolata, abaxial epidermis of leaf blade with peculiar silica bodies: this project. • Scrotochloa urceolata, abaxial epidermis of leaf blade: this project. 'Scrotochloa-type' silica bodies.

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: 15th June 2025. delta-intkey.com’.

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