Manihot Manihotoides (Euphorbiaceae) - CNCFlora

18 Flora Neotropica
specimen for accurate assignment. Dimensions of foliaceous, semifoliaceous and setaceous
bracts are not significant as means of differentiation, but the qualitative terms are suf-
ficiently descriptive to provide the user with good differentiating ability.
Staminate flower
The flowers of the species of Manihot are remarkably uniform in their morphology
(refer to discussion in the section Biology of Speciation). The staminate flowers are
generally toward the apex of any inflorescence.
The outline of the staminate flower buds is a good differentiating character. Their
shapes are described in character 37. The flowers are characterized by a single perianth
whorl in all species, called tepal in this monograph. The term does not indicate whether
the perianth whorl is either calyx or corolla, and there is some doubt as to the origin of
the tepal. Generally the term infers calycine origin. In the staminate flower, the tepals are
united for about one half their length, and the lobes of the tepals are either erect,
spreading, or reflexed. The stamens are generally ten (sometimes eight) in number, in two
whorls. The slender filaments support versatile anthers with two longitudinally dehiscing
thecae. The large pollen grains are generally sticky, and polyforate, the sculpturing
consisting of round or triangular verrucae. The disc of the staminate flower is lobed, with
the filaments arising between the lobes. Generally, a small pistillode is found in the center
of the disc. There are differences in overall size of the flowers, variations in pubescence,
and in color. Pubescence of the flowers are adequately reflected in characters 7, 8 and 9.
Pistillate flower
Pistillate flowers occupy the lower portion of the inflorescence. There may be a bare
space along the major inflorescence axis before the appearance of a pistillate flower, or
the pistillate flowers may be inserted very near the base of the inflorescence. The relative
positions of insertion of the pistillate flowers are employed in character 40.
The tepals of the pistillate flower are free, 5-merous, generally linear, apices acute,
variously glabrous to pubescent most prominently along the inner margins. The disc of
the female flower is generally smooth, not lobed. The 3-carpellate, 3-locular ovary
generally has one pendulous, anatropous ovule per locule. The three-lobed stigma is sessile
or nearly so. The shape and size of the structures of the pistillate flower are generally
quite uniform among the species.
Fruit and seed
The fruit is a capsule, with septicidal and (usually) loculicidal dehiscence. The
surface of the fruit is generally smooth, sometimes more or less prominently 3-winged or
ribbed. The shape is generally ovoid to ellipsoid, but certain species have obpyriform
fruits. The apex of the fruits may be depressed, rounded, or acute. The size of the fruit,
the shape of the apex, and the presence or absence of wings are the only characters
available as systematic criteria.
The carunculate seeds are typically euphorbiaceous. Their surface may be plain or
mottled, but the degree of mottled pattern depends to some extent upon the maturity of
the seeds. The caruncle and the whole seed vary in dimension and shape, and these are the
only available characters of sufficient stability to use in the classification.