LENNOACEAE

the sand food family, composed of three genera and four to six species of curious, parasitic plants, which send out rootlike structures (haustoria) that penetrate the roots of other plants for food. Once the parasite's haustoria have entered the host roots, the parasite develops its aboveground portions, usually club-shaped, fleshy, yellowish or brownish stems on which a head of flowers appears. The scalelike leaves lack chlorophyll. Two species of Lennoa in Mexico are typical. Flor de tierra (flower of the earth; L. madreporoides) is highly selective, growing usually on roots of the Mexican sunflower (Tithonia). The oval, mushroomlike stem is 515 cm (26 inches) tall, yellowish or brownish in colour, and covered with oval to lance-shaped scales. The plant's domelike head is covered at maturity with small, starlike flowers, violet with yellow throats. It is native in cornfields of south-central Mexico, at about 1,500 m (5,000 feet) altitude. A blue-flowered species, L. caerulea, grows on higher land, near Mexico City and Puebla. Two genera occur in southwestern North America: sand food (Ammobroma) and desert Christmas tree (Pholisma).