California Croton

California croton (Croton californicus) is a low-growing, grayish-green plant with small, inconspicuous flowers. Male and female flowers occur on different plants. California croton is native to the southwestern United States and northern Mexico. It is a plant of sandy areas and can be seen in several low, sandy areas in the Reserve.

In spite of its generally drab appearance, the foliage is covered with a carpet of shining stellate hairs, each a tiny starburst. The hairs not only deter grazers, but also protect the plant from the environment; they reflect the sun, thereby cooling the plant, and they protect the leaves from the full force of the wind, thereby reducing water loss.

Description ^2,4,11,26,59

California croton is a low-growing, short-lived perennial, woody at the base. Plants reach three feet (1 m) high, but those in the Reserve usually hug the ground. The foliage, stems and fruit are grayish-green and covered with tiny, scale-like, star-shaped hairs that give the plant a sheen. Leaves are oval to ovate, usually less than 2 inches (5 cm) long and 1 inch (2.5 cm) wide with smooth margins.

Male and female flowers are produced on separate plants. The inconspicuous greenish-white colored flowers occur in clusters of few to many flowers at the leaf axils toward the ends of branches. Flowers are small, about 1/8 inch (0.3 cm) across, and lack petals; the sepals form a shallow cup with five lobes. The male flower has 10-15 stamens; the female flowerhas a pistil with a three-lobed ovary and three styles, each of which is branched into several (<9) terminal, tentacle-like segments. The reported flowering time is May – October,⁷ but flowers may be found all year.

The fruit is a three lobed capsule with an irregularly bumpy surface. When mature, it splits into three segments from the central axis, each segment releasing one seed. Seeds are a somewhat compressed ovoid, smooth and more or less mottled, with a fleshy appendage near the point of attachment (caruncle or elaiosome).

Classification ^11,44,59,143

Croton is a dicot angiosperm in the spurge family (Euphorbiaceae). This is a large, diverse group containing small herbs, vines, cactus-like succulents, shrubs and trees. Many euphorbias contain a clear or milky sap that is toxic or irritating. Flowers often lack petals, although some species have colorful bracts or glands that function as petals. Flowers are unisexual. Male and female flowers may be on the same plant (plants are “monoecious”) or on separate plants (plants are “dioecious”). The male flowers may have numerous stamens. The pistil of the female plant has three styles; the superior ovary is usually three-lobed and ripens into a dry three-chambered capsule that splits open on maturity releasing one seed per chamber.

The spurge family contains a variety of decorative, useful and annoying species, including the cheerful, holiday poinsettia (Euphorbia pulcherrima), the entertaining Mexican jumping bean (Sebastiania pavoniana), the deadly castor bean (Ricinus communis) and the omnipresent garden weed, spotted spurge (Euphorbia maculata). Other native euphorbias in the Reserve are doveweed (Croton setiger), and cliff spurge (Euphorbia misera). Non-natives include castor bean and a variety of weedy species, including the spotted spurge.

The genus Croton is a large and complicated genus. Recently, The Croton Project was established to bring botanists and ecologists together to clarify the taxonomy and phylogeny of the genus.²¹⁸ Currently, members of the Croton genus are characterized by the development of the stamens and, to a large extent, by the presence of stellate hairs. Unlike many members of the spurge family, California croton lacks milky sap and is not known to be toxic.²⁰⁹ However, there are colorful house plants also called croton (Codiaeum spp.) that contain “quite a cocktail of bad stuff” which cause dermatitus and, if ingested, can be toxic to both  pets and humans.^215,216

Ecology ^41,217

Many plants have hairs on their stems and/or leaf surfaces. These are thought to protect the plant by physically impeding chewing insects. Certainly the network of stellate hairs on the Croton leaf would appear to be a formidable barrier for a small grazer.

In our climate, where the summers are long and dry, an equally important purpose may be to protect the plant from environmental extremes. Hairs reflect the hot sun from the leaf surface, keeping the leaf cool, and they shelter the leaf surface from desiccating winds, reducing water loss.

Human Uses

In Southern California and northern Baja, native Americans used croton for a variety of medical problems. Locally, the Kumeyaay made a tea of the entire plant and used it as an eye wash and a treatment for pink eye.¹⁶ In Baja, they drank a tea for a cough,²¹⁹ and the Chumash drank a tea for “colds”.¹⁵ The Luiseño used croton to induce abortion.¹⁷ Other tribes made a salve which was rubbed on the skin for rheumatism,¹⁵ or used as a poultice for earaches.³⁴

Interesting Facts ²¹

The genus name, Croton, is derived from the Greek word for “tick”. Apparently seeds of some species of Croton resemble those tiny, unpleasant parasites.