The following Participating Institutions are custodians for this species in the CPC National Collection:
San Antonio Botanical Garden
The conservation of Manihot walkerae is fully sponsored.
Cindy Barrett contributed to this Plant Profile.
Manihot walkerae is an endangered plant in South Texas and parts of Mexico (USFWS 1993). It is related to other Manihot species which are grown in Third World countries in order to provide cassava, an important source of starch for millions of people. The roots must first be boiled in order to extract poisonous, possibly fatal, acids. Tapioca is a product derived from cassava. Manihot walkerae is the most cold hardy of the Manihots. Crossing this species with others may increase the growing range of those Manihots used as a food source. Manihot walkerae may also contain important disease resistant genes. (USFWS 1993).
Separate female and male flowers occur on the same plant, with all flowers blooming from April to September following rain. Male flowers occur on elongated stems and are white with light purple streaks. They have five lobes, are nearly 1/2 inch long, and are shaped as tubes. Female flowers, much smaller than male flowers at only 3/8 of an in long, occur at the base of the long stalks of the male flowers. (Texas Parks and Wildlife 2002)
Distribution & Occurrence
Found in the Tamaulipan Biotoic province, on mesic upland in or near dense stands of native brush, which create a microclimate of shade, protection from trampling/grazing, and lower temperatures,.
| Found in four locations in Hidalgo and Starr Counties in Texas. One is located on private land, and contains only one plant, the other three are located in the Lower Rio Grande National Wildlife Refuge. (Texas Parks and Wildlife 2002)
Two populations are known from northern Tamaulipas, Mexico. (USFWS 1993)
Conservation, Ecology & Research
Separate male and female flowers occur on the same plant--the single plant in Hidalgo County, Texas, has produced seed, so the species is hypothesized to be self-fertile. However, the flowers are reportedly fragrant. Possible pollinators are unknown. (Texas Parks and Wildlife 2002)
Response to disturbance
Seed dispersal and seedling recruitment
Rogers, D.J.; Appan, S.G. 1973. Flora Neotropica, Monograph No. 13. Manihot [and] Manihotoides (Euphorbiaceae). New York: Hafner Press.