Manihot esculenta
Manihot
bitter cassava, cassava, manioc, tapioca
cassava, manioc, yuca
thickened.
erect, terete when young;
nodes conspicuously swollen;
leaf and stipule scars elevated, especially on older stems.
persistent;
stipules lanceolate, entire;
petiole 3–20 cm;
blade basally attached, usually 3–10-lobed, sometimes unlobed, lobes without secondary lobes, median lobe 5–18 cm, margins neither thickened nor revolute, entire to ± repand, apex acuminate, surfaces glabrous or hairy, abaxial finely reticulate.
persistent or deciduous, alternate, simple [palmately compound];
stipules present, deciduous;
petiole present [rudimentary], glands absent;
stipels present at apex;
blade usually palmately lobed, rarely unlobed, lobes undivided or secondarily lobed, margins entire, repand, or serrate, laminar glands absent;
venation palmate (pinnate in lobes).
axillary, panicles, 2–10 cm.
bisexual (pistillate flowers proximal, staminate distal), terminal or axillary, racemes or panicles;
glands subtending each bract 0.
staminate 2–4 mm; pistillate 20 mm in fruit, straight.
present, pistillate often elongating in fruit.
calyx campanulate, 10–15 mm, lobes erect or spreading;
stamens 10.
sepals 5, petaloid, 7–20 mm, valvate, connate 1/2 length;
petals 0;
nectary intrastaminal, cushion-shaped, lobed;
stamens (6–8)–10, in 2 whorls, distinct;
pistillode absent.
sepals 5, petaloid, distinct;
petals 0;
nectary annular, lobed or unlobed;
pistil 3-carpellate;
styles 3, connate basally, unbranched, flabellate, prominently papillate.
capsules.
1.5 cm, usually winged.
subglobose to oblong, 12 mm.
globose to oblong;
caruncle present.
= 9.
= 36.
Manihot esculenta
Manihot
The enlarged storage roots of Manihot esculenta yield a starchy staple, now much consumed in tropical regions around the world. Tapioca, a pelletized and partially hydrolyzed form of cassava starch, is the chief form of consumption in temperate regions. Multiple cultivars are known. These are generally characterized as bitter (containing cyanogenic glycosides, which must be removed before consumption) or sweet (cyanogenic glycosides absent or at low levels). A form with variegated leaves is sometimes grown for ornament. Cassava was cultivated throughout the Neotropics in pre-Columbian times. As a root crop with poor storage qualities adapted to humid regions, archeological remains are few, leading to much speculation in the literature about the origin of this important crop. Molecular data reported by K. Olsen and B. A. Schaal (1999, 2001), indicate that cultivated cassava constitutes M. esculenta subsp. esculenta, derived by artificial selection from its sole wild ancestor, M. esculenta subsp. flabellifolia (Pohl) Ciferri from the southern border of the Amazon basin. Under this classification, all North American plants belong to subsp. esculenta.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species ca. 100 (6 in the flora).
Manihot is one of the most economically important members of Euphorbiaceae, primarily because of the starchy food-bearing roots of M. esculenta, now cultivated throughout the tropics. Also, M. glaziovii Müller Arg., from northeastern Brazil, was once an important source of Ceará rubber. Manihot appears to be most closely related to Cnidoscolus, a conclusion supported by morphological (G. L. Webster 1994) and DNA sequence data (K. Wurdack et al. 2005). Four species of sect. Parvibracteatae, as defined by D. J. Rogers and S. G. Appan (1973), barely extend across the borders of Arizona and Texas from Mexico. In addition, two species are naturalized in the southeastern United States.
Leaf blade lobe characters (length, outline) are best developed in the median and immediately adjacent lobes; lateral lobes are progressively smaller and tend to have simpler outlines with distance from the median lobe.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Shrubs or trees; inflorescences panicles; Gulf and Atlantic coastal plains. | → 2 |
2. Leaf blade lobes without secondary lobes; stipules lanceolate, entire; stem nodes conspicuously swollen; leaf and stipule scars elevated, especially on older stems; capsules usually winged. | M. esculenta |
2. Median and adjacent leaf blade lobes with secondary lobes, lateral lobes without secondary lobes; stipules linear, remotely serrate; stem nodes not swollen; leaf and stipule scars not elevated; capsules not winged. | M. grahamii |
1. Herbs or subshrubs; inflorescences racemes; Texas and Arizona. | → 3 |
3. Leaf blade secondary lobes acute, proximal; leaf blade margins remotely serrate. | → 4 |
4. Leaf blade margins neither thickened nor revolute; inflorescences axillary; capsules finely tuberculate; s Arizona and adjacent Mexico. | M. angustiloba |
4. Leaf blade margins thickened and revolute; inflorescences terminal; capsules smooth; s Texas and adjacent Mexico. | M. subspicata |
3. Leaf blade secondary lobes rounded, distal or distal and proximal to middle; leaf blade margins entire. | → 5 |
5. Leaf blades basally attached; staminate calyces campanulate; capsules nearly smooth; s Arizona and adjacent Mexico. | M. davisiae |
5. Leaf blades peltate; staminate calyces tubular, midsection constricted; capsules verrucose-rugose; s Texas. | M. walkerae |
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