23. Stillingia Garden in C. Linnaeus, Mant. Pl. 1: 19, 126. 1767. Syst. Nat. ed. 12, 2: 611, 637, 1767.
[For Benjamin Stillingfleet, 1702–1771, British botanist] [For Benjamin Stillingfleet, 1702–1771, British botanist]
Michael J. Huft
Herbs, subshrubs, or shrubs [trees], annual or perennial, monoecious; hairs absent [rarely glandular]; latex white. Leaves deciduous, alternate, opposite, or subopposite [whorled], simple; stipules absent or present, persistent; petiole absent or present, glands absent [small sessile gland at apex]; blade unlobed, margins entire, dentate, crenate, serrulate, or spinulose-dentate, laminar glands absent; venation pinnate. Inflorescences bisexual (pistillate flowers proximal, staminate distal), terminal, spikes or spikelike thyrses; glands subtending each bract 2. Pedicels absent. Staminate flowers: sepals 2, imbricate, connate basally; petals 0; nectary absent; stamens 2, connate basally; pistillode absent. Pistillate flowers: sepals 0 or [2–]3, distinct; petals 0; nectary absent; pistil [2–]3-carpellate; styles 3 [rarely 2], connate proximally, unbranched. Fruits capsules base persisting as [2–]3-lobed gynobase, glabrous. Seeds globose, ovoid, ellipsoid, or cylindric, ± flattened or depressed at hilar end; outer seed coat dry; caruncle absent or present. x = 11.
Species ca. 33 (7 in the flora): s United States, Mexico, West Indies, Central America, South America, Indian Ocean Islands (Madagascar), Pacific Islands (Fiji Islands).
Stillingia is distributed primarily in the warmer regions of the western hemisphere, with a major center of diversity extending from the southwestern United States through Mexico to northern Central America and another occupying the region of southern Brazil, northern Argentina, and Paraguay. Other New World species occur in Peru, southern Central America, and the southeastern United States. Outside of the western hemisphere, there are three species in Madagascar and one in Fiji. Among species in the flora area, only S. sylvatica is widespread, ranging throughout much of the southern United States from Virginia to New Mexico.
Stillingia is one of the more distinctive genera in the tribe Hippomaneae A. Jussieu ex Spach, which are generally characterized by the presence of white latex and by terminal or axillary spikelike inflorescences with one or more solitary basal pistillate flowers. Among these genera, Stillingia is distinguished by the presence of a gynobase, the hardened proximal portion of the ovary that remains as a 3-parted (or 2-parted in a few species outside the flora area) persistent base attached to the pedicel after dehiscence of the fruit. The circumscription of Stillingia has remained essentially unchanged since 1880, when Bentham first recognized the importance of the gynobase as the most important distinguishing character (D. J. Rogers 1951).
SELECTED REFERENCE Rogers, D. J. 1951. A revision of Stillingia in the New World. Ann. Missouri Bot. Gard. 38: 207–259.