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castor oil plant, castor-bean

castor bean, castor oil plant, ricinus

Habit Plants 1–4[–5+] m. Stems erect. Herbs [shrubs], annual or perennial, monoecious; hairs absent; latex absent.

stipules 2–3 cm, connate, leaving conspicuous scar around stem;

petiole 10–55 cm, with (0–)1–3 cuplike glands on proximal adaxial surface, 2 glands at apex adaxially;

blade circular in outline, 15–50 cm diam., base peltate, marginal teeth gland-tipped, laminar glands scattered on adaxial surface, lobes 7–12, lanceolate or oblanceolate, increasing in size apically, apex narrowly acute to acuminate.

deciduous, alternate, simple;

stipules present, caducous;

petiole present, glands present at apex and usually proximally;

blade palmately lobed, margins serrate, laminar glands present;

venation palmate.


6–30 cm, to 45 cm in fruit;

bracts caducous except for 2 persistent glands.

bisexual (staminate flowers proximal, pistillate distal) or pistillate, terminal or leaf-opposed, racemelike thyrses;

glands subtending each bract 2.


staminate 5–15 mm; pistillate 0.5–5 mm, elongating to 40 mm in fruit.


Staminate flowers

calyx lobes ovate, 7–8 mm;

stamen cluster ± spheric, 10–12 mm diam.

sepals 3–5, valvate, connate basally;

petals 0;

nectary absent;

stamens to 1000, connate proximally in numerous slender, irregularly branched columns;

pistillode absent.

Pistillate flowers

sepals ovate, 4–5 mm;

ovary densely covered in slender-conic, bristle-tipped outgrowths;

styles red or orange-red, 4–5 mm;

stigmas distinctly spreading, papillose.

sepals 5, distinct or connate basally;

petals 0;

nectary absent;

pistil 3-carpellate;

styles 3, distinct or slightly connate basally, 2-fid.




dark red, echinate, subglobose, 1.5–2 cm diam.


mottled brown, 8–11 mm, shiny.

ovoid or ovoid-ellipsoid;

caruncle present.


= 10.


= 20.

Ricinus communis


Phenology Flowering and fruiting summer–late fall.
Habitat Waste ground, riverbanks, sand and gravel bars, ravines, margins of cultivated fields, roadsides, along railways.
Elevation 0–700 m. (0–2300 ft.)
from FNA
AL; AR; AZ; CA; FL; GA; LA; MO; MS; TX; Africa [Introduced in North America; introduced also in Mexico, West Indies, Bermuda, Central America, South America, Eurasia, Atlantic Islands, Indian Ocean Islands, Pacific Islands, Australia]
[WildflowerSearch map]
[BONAP county map]
from USDA
ne Africa; widely cultivated and often naturalized in tropical; subtropical; and warm temperate regions worldwide [Introduced in North America]
[BONAP county map]

Ricinus communis, native to northeastern Africa, is cultivated as an ornamental throughout subtropical and temperate North America and is naturalized in the southern United States. It has been reported throughout the eastern United States as far north as Michigan and New Hampshire, and north to Utah and Kansas farther west, but appears to be a nonpersisting garden escape that is only adventive and not naturalized in these areas. In Missouri, it is considered to be naturalized (and uncommon) only in the extreme southeastern corner. Plants are shrubs in tropical and subtropical regions and very large annual herbs in cooler regions. Numerous horticultural cultivars exist, including some with dark red stems and leaves that are commonly planted in North America.

All plant parts are poisonous due to the water soluble protein ricin. In tropical regions (mainly Brazil and India), the species is widely cultivated for its seed oil. Castor oil, derived from the seeds (highly refined oil does not contain ricin), is used in cosmetics, medicines, paints, plastics, and lubricants. The use of castor oil in traditional medicine dates at least from ancient Egyptian times. Castor oil is used worldwide for a variety of medicinal purposes, most commonly as a laxative and for skin ailments. In North America, it was formerly commonly given to children as a general cure-all for internal ailments.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species 1.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 12, p. 160. FNA vol. 12, p. 160. Author: Lynn J. Gillespie.
Parent taxa Euphorbiaceae > Ricinus Euphorbiaceae
Subordinate taxa
R. communis
Name authority Linnaeus: Sp. Pl. 2: 1007. (1753) Linnaeus: Sp. Pl. 2: 1007. (1753): Gen. Pl. ed. 5, 437. (1754)
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