Votomita
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Authority
Morley, Thomas. 1976. Melastomataceae tribe Memecyleae. Fl. Neotrop. Monogr. 15: 1-295. (Published by NYBG Press)
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Family
Melastomataceae
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Scientific Name
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Type
Type species. Votomita guianensis Aublet.
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Synonyms
Glossoma Schreb., Guilleminia Neck., Meliandra, Glossocoma Endl., Coryphadenia
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Description
Description - Shrubs to trees, mostly glabrous; branchlets terete to narrowly 4-winged; stone cells present in pith and cortex at node, extending into the internode and along the midrib to the leaf apex; node unilacunar. Leaves decussate, short-petiolate, estipúlate or sometimes with a minute interpetiolar fringe; blades with revolute vernation, oblong-elliptic to elliptic to ovate to subrotund, sometimes irregularly translucent-speckled when held to light, the speckles apparently the terminal sclereids within, blades pinnate-nerved, sometimes only the midrib apparent, the latter sometimes pubescent below; margins of xylem of petiole, midrib, and lateral veins fused above to form a tube; stomata superficial or in crypts or both, when present often with 2-6 cavities per crypt; sclereids terminal on the vein endings present in the blade, the sclereids from irregularly short-branched to long-armed to columar, sometimes accompanied by or greatly outnumbered by unattached sclereids of the same general type, in V. monadelpha accompanied by unattached sclereids of a different form from the attached ones; epidermises from one to three cell layers thick, the cells polygonal in surface view, their inner walls often mucilage-thickened; hypodermis present or absent, when present, without mucilage walls. Flowers pedicellate in 1-3-(-4)-flowered cymes; two minute bracts sometimes present at base of pedicel; peduncles one to several at the leaf axils, on wood of the current or preceding year. Flowers 4-merous, in one species sometimes abnormally 5-merous and rarely 6-merous; free hypanthium none; calyx limb bowl-shaped, usually with 4 small teeth that are free early in the bud. Petals 4, mostly convolute in aestivation, seldom irregularly imbricate, white or whitish, pink, or violet, often papillose toward the apex, containing numerous box-shaped stone cells unattached to the veins. Stamens 8, equal or nearly so, sometimes laterally fused; filaments very short, not inflexed in bud; anthers straight, erect, the connective produced above the sporangia, usually bearing distally an elliptic introrse gland; sporangia 4, adaxial, straight, dehiscing by lengthwise introrse slits; vascular trace with no major branches. Ovary 1-4-locular; placentation axile or free-central or the ovules in a whorl around an axile or basal placenta in each locule, when free-central the ovules in one whorl at the top of the placenta; ovules bent at a sharp angle from a broad chalazal attachment, 5-14 per locule, 5-48 per ovary; style usually soon deciduous, persistent in at least 1 species. Fruit a 1-seeded berry in the two examples known, crowned by the persistent calyx and by the style in one species. Inner and outer faces of the ovule enlarging about equally during development into a seed, the outer face in the seed slightly elevated in contrast to the inner, the surfaces slightly roughened, unpolished; radicle short and straight, the cotyledons thick, fleshy, and plano-convex. Floral terminal sclereids present, frequent to rare.
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Discussion
An overall view of the genus now shows three species in Amazonia, one in Surinam which may be the same as one of the Amazonian ones, one in French Guiana and Surinam, one in southern Venezuela, and one in Cuba. Of these plants two, V pterocarpa and V. monadelpha, have certain features in common, namely a midrib that is pubescent below on the sides and winged on the lower angles, large flowers, monadelphous stamens, 3 or 4 locules, and many ovules; the two are apparently rather closely related. They must be regarded as unspecialized in their large flowers with several locules and a large number of ovules and in the pentamery common in V. monadelpha, but surely are specialized in their stomatal crypts and especially in the lateral fusion of the anthers. Probably V. plerocarpa may be considered the most primitive of the two because of its unspecialized axile placentation, although it has fixed tetramery; V. monadelpha has unstable tetramery but has an advanced placentation. A third Amazonian species, V. orbinaxia, lacks the pubescent winged midrib and monadelphous stamens of the preceding plants and has somewhat smaller flowers but has retained a 4-locular ovary and has a unique placentation for the tribe, axile but with the ovules in vertically oriented whorls. This placentation may have preceded that of V. monadelpha, the placentae in the latter species having then presumably been brought to a basal position through the same process of differential growth that produced similar forms in Mouriri; or the placentation of V. orbinaxia and V monadelpha could have been brought about independently; it is uncertain which interpretation is correct. Neither species with axile placentation appears to represent a beginning point for the genus, V. plerocarpa because of its fused stamens and V. orbinaxia because of the whorled arrangement of the ovules on the placenta, an arrangement I regard as specialized because it can only be a derivative of the primitive axile condition and because it occurs only in the most specialized members of Mouriri
The three remaining species of Votomita are generally more specialized than the preceding ones and are also more peripheral to Amazonia. They are more specialized in having smaller flowers with 1-locular ovaries; the midribs are glabrous and the stamens are free as in V. orbinaxia. The flowers of all seem at about the same level of reduction; however, V. guianensis could be regarded as the least specialized of them on the basis of its stomata which are superficial or in simple shallow crypts. The other two species are similar to each other, but V. orinocensis can be considered slightly less specialized than V. monantha because of the former’s lack of a hypodermis in the leaf, its more slender pedicels, its more fully developed anther glands, and its deciduous style. See Fig 90 for the distributions.