Platostoma

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Platostoma
Platostoma africanum P. Beauv, crop.jpg
Platostoma africanum
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Lamiales
Family: Lamiaceae
Subfamily: Nepetoideae
Tribe: Ocimeae
Genus: Platostoma
P.Beauv. (1818)
Species [1]

51; see text

Synonyms [1] [2]
  • AcrocephalusBenth. (1829)
  • CeratanthusF.Muell. ex G.Taylor (1936)
  • GeniosporumWall. ex Benth. (1830)
  • HemsleiaKudô (1929)
  • LimnibozaR.E.Fr. (1916)
  • MesonaBlume (1826)
  • NosemaPrain (1904)
  • OctomeronRobyns (1943)

Platostoma is a genus of flowering plants in the mint family, Lamiaceae, first described as a genus in 1818. It is native to tropical parts of Africa, southern Asia, Papuasia, and Australia. [2] Mesona [3] [4] and Acrocephalus has been known as its synonyms.

Contents

A widely consumed species in this genus is Platostoma palustre (synonyms Mesona chinensis, M. elegans, and M. procumbens), [5] or xiancao (仙草) in Mandarin, sian-chháu (仙草) in Taiwanese, leung fun cho (涼粉草) in Cantonese, sương sáo in Vietnamese, and cincau in Indonesian and Malay. It is eaten as a snack in drinks, or set as a gel and served as a grass jelly.

In Indonesia the Platostoma palustre leaf is used to make a black jelly; there is also an instant powder variety available.

Description

Annual or perennial herbs with stems arising from a taproot, slender rhizome, or small woody rootstock; stems usually annual. Upper leaves and bracts often basally pale or coloured. [6]

Inflorescence lax or condensed, with verticils of opposite cymes, the cymes usually bearing more than three flowers. Calyx round in cross-section; posterior lip 1- or 3-lobed, the posterior lobe decurrent or not; anterior lip 1–5-lobed. Corolla curved, dorsally gibbous or spurred; posterior lip 3- or 4-lobed and ascending, anterior lobe horizontal. Stamens four, declinate or spreading, with filaments basally swollen or bearing a flattened basal appendage, often pubescent. Style bifid. [6]

Nutlets minutely striate or reticulate, apically pubescent or glabrous. [6]

Taxonomy

The genus is divided into three subgenera and several sections. [6]

Subgenus Acrocephalus

Fruiting calyx throat open; posterior lobe rounded or shallowly emarginate, decurrent or not. Calyx lobes arranged as either a single posterior lobe with four anterior lobes, or three posterior lobes with two anterior lobes. Corolla dorsally gibbous. Stamens declinate; posterior filament attached near the midpoint of the corolla tube, inappendiculate. [6]

Section Acrocephalus

Nutlets apically glabrous. [6]

Section Heterodonta

Nutlets apically pubescent or tuberculate. [6]

Subgenus Octomeron

Fruiting calyx throat open. Posterior lobe rounded, shortly decurrent; lateral lobes closer to the posterior lobe than to the five lobes of the anterior lip, forming a 3-lobed posterior lip and a 5-lobed anterior lip. Corolla dorsally gibbous. Stamens declinate; posterior filament attached near the midpoint of the corolla tube, without appendages. Nutlets glabrous. [6]

Subgenus Platostoma

Fruiting calyx throat closed. Posterior lobe acute, rounded or emarginate, decurrent or not. Lateral lobes usually close to the posterior lobe, forming a 3-lobed posterior lip and a 1-lobed anterior lip; less often midway between posterior and fused median anterior lobes or much reduced. Corolla dorsally gibbous or spurred. Stamens declinate or spreading; posterior filament attached near the base or midpoint of the tube, appendiculate or not. Nutlets apically glabrous. [6]

Section Platostoma

Posterior calyx lobe rounded and shortly decurrent; lateral lobes much reduced and close to the posterior lobe, giving a 1-lobed posterior lip and a 1-lobed anterior lip. Corolla dorsally gibbous. Stamens declinate; posterior filament inappendiculate, attached near the midpoint of the corolla tube. Nutlets apically rounded. [6]

Section Ceratanthus

Posterior calyx lobe rounded and shortly decurrent; lateral lobes variable, either much reduced giving a 1-lobed posterior lip and a 1-lobed anterior lip, more prominent and close to the posterior lobe giving a 3-lobed posterior lip and a 1-lobed anterior lip, or more rarely positioned midway giving a 1-lobed posterior lip and a 3-lobed anterior lip. Corolla usually spurred, sometimes dorsally gibbous. Stamens declinate; posterior filaments inappendiculate, attached near the base of the corolla tube. Nutlets apically rounded. [6]

Section Limniboza

Posterior calyx lobe acute and not decurrent; lateral lobes close to the posterior lobe, forming a 3-lobed posterior lip and a 1-lobed anterior lip. Corolla dorsally gibbous. Stamens declinate or spreading, with inappendiculate posterior filaments attached near the midpoint of the corolla tube. Nutlets apically rounded. [6]

Section Mesona

Posterior calyx lobe acute, rounded or emarginate, decurrent or not; lateral lobes close to the posterior lobe, forming a 3-lobed posterior lip and a 1-lobed anterior lip. Corolla dorsally gibbous. Stamens declinate; posterior filaments usually appendiculate, rarely inappendiculate, and attached near the midpoint of the corolla tube. Nutlets apically acute. [6]

References

  1. 1 2 Platostoma P.Beauv. Plants of the World Online . Retrieved 15 April 2024.
  2. 1 2 Kew World Checklist of Selected Plant Families
  3. ↑ Quattrocchi, Umberto (2012). World Dictionary of Medicinal and Poisonous Plants. CRC Press. p. 2489. ISBN   978-1-4200-8044-5. See Bijdragen tot de flora van Nederlandsch Indië 838. 1826 and Taiwania 43(1):38–58. 1998.
  4. ↑ Don, George (1838). General History of the Dichlamydeous Plantus. London. p. 675. from μέσος, mesos, middle; so called because the genus was supposed by the author to be intermediate between Ocimum and Scutellaria .
  5. ↑ Flora of China
  6. 1 2 3 4 5 6 7 8 9 10 11 12 13 Paton, Alan (1997). "Classification and Species of Platostoma and Its Relationship with Haumaniastrum (Labiatae)". Kew Bulletin. 52 (2). Royal Botanic Gardens, Kew: 257–292. doi:10.2307/4110385.
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