| # The grass genera of the world |

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

### Porteresia Tateoka

Named for R. Portères, specialist on Oryza.

~ Oryza (O. coarctata)

Including Sclerophyllum Griff., Indoryza Henry & Roy

Habit, vegetative morphology. Perennial. Culms herbaceous. Leaf blades narrowly linear; leathery (with tuberculate prickly margins); without cross venation.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.

Inflorescence. Inflorescence narrowly paniculate; open; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.

Female-fertile spikelets. Spikelets unconventional (owing to extreme reduction of the glumes, cf. Oryza); elliptic; strongly compressed laterally; disarticulating above the glumes (if the pedicel cup be interpreted as glumes); with conventional internode spacings (i.e. the floret not stipitate). Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes present to absent (discernable only as obscure lobing of the pedicel tip); if considered present, two; minute; more or less equal; shorter than the adjacent lemmas; joined; awnless. Lower glume 0 nerved. Upper glume 0 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 2; epaleate; sterile (much reduced, cf. Oryza). The proximal lemmas awnless; exceeded by the female-fertile lemmas (less than half the length of the spikelet).

Female-fertile florets 1. Lemmas leathery; not becoming indurated; shortly aristulate; strongly carinate; 5–10 nerved. Palea present; relatively long (resembling the lemma); awnless, without apical setae; textured like the lemma; several nerved; one-keeled. Lodicules present; 2; membranous. Stamens 6. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Hilum long-linear. Embryo large. Endosperm hard. Embryo with an epiblast (large); with a scutellar tail; with a negligible mesocotyl internode; with one scutellum bundle. Embryonic leaf margins overlapping.

Abaxial leaf blade epidermis. Papillae present. Microhairs absent. Costal silica bodies not sharp-pointed.

Transverse section of leaf blade, physiology. Leaf blades seemingly consisting of midrib (with two superposed bundles in each rib, the adaxial one being inverted, and large air spaces in the mesophyll).

C3; XyMS+. Mesophyll with arm cells; without fusoids. Midrib having complex vascularization (regardless of whether or not the blade is interpreted as midrib, since every rib has superposed bundles). Bulliforms present in discrete, regular adaxial groups.

Cytology. Chromosome base number, x = 12. 2n = 48. 4 ploid.

Classification. Watson & Dallwitz (1994): Bambusoideae; Oryzodae; Oryzeae. Soreng et al. (2015): Oryzoideae (as a synonym); Oryzeae; Oryzinae. 1 species (P. coarctata).

Distribution, phytogeography, ecology. India, Burma.

Helophytic; halophytic (in the brackish waters of deltas and tidal swamps).

References, etc. Morphological/taxonomic: Tateoka 1965a.

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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