11. Sicyos Linnaeus, Sp. Pl. 2: 1013. 1753; Gen. Pl. ed. 5, 443. 1754.
Bur cucumber [Greek sikyos, cucumber or gourd] Bur cucumber [Greek sikyos, cucumber or gourd]
Plants annual, monoecious, climbing or trailing; stems glabrous or hairy, often viscid-pubescent when young; roots fibrous; tendrils 2–5-branched from a common point. Leaves <sessile or subsessile to petiolate>; blade ovate or orbiculate to suborbiculate or reniform, deeply to shallowly palmately 3–5-angular-lobed, lobes triangular to deltate, margins usually serrate to denticulate, surfaces eglandular. Inflorescences: staminate flowers 3–22(–34) in axillary racemes or panicles; pistillate flowers 4–16, sessile to subsessile in umbelliform clusters at peduncle apex, from same axils as staminate, <peduncles erect at apex>; bracts absent. Flowers: hypanthium cupulate to shallowly campanulate; sepals 5, ovate to deltate or subulate, linear, linear-triangular, or narrowly triangular; petals 5, connate 1/4–1/2 length, white to greenish white, yellowish green, or yellow, triangular to lanceolate or narrowly lanceolate, 0.5–1.5 mm, glabrous abaxially, often glandular adaxially, corolla campanulate to cupulate. Staminate flowers: stamens (2–)3(–5); filaments inserted at base of hypanthium, connate 1 mm; thecae connate into head, horseshoe-shaped, connective slightly broadened; pistillodes absent. Pistillate flowers: ovary 1-locular, ovoid-fusiform; ovules 1 per locule; style 1, narrow; stigmas 1, obscurely 2–3-lobed; staminodes absent. Fruits pepos, dark green to gray at maturity, fusiform to ovoid, <beaked or not, dry, thin-walled>, echinate or spinulose, <usually also with shorter hairs, rarely glabrous>, indehiscent. Seeds 1, ovoid, compressed, not arillate, margins not differentiated but sometimes with 2 small swellings at base, surface smooth. x = 12.
Species ca. 50 (4 in the flora): North America, Mexico, Central America, South America, Pacific Islands, Australia; introduced in Europe, e Asia.
Attribution of Sicyos parviflorus A. Gray ex Naudin to the United States has been based on misapplication of the name. The type of S. parviflorus was collected from the vicinity of Mexico City, and the species occurs from central Mexico through Central America into South America (R. Lira 2001).
SELECTED REFERENCE Nesom, G. L. 2011. Taxonomy of Sicyos (Cucurbitaceae) in the USA. Phytoneuron 2011-15: 1–11.