Cevallia is a monotypic genus of flowering plants in the family Loasaceae (order Cornales), containing the single species Cevallia sinuata. Described by Spanish botanist Mariano Lagasca in 1805, it was published in Variedades de Ciencias, Literatura y Artes (vol. 2, no. 4, p. 36). The sole species is commonly known as stinging serpent.
Members are shrubs or suffrutescent perennials reaching up to 1 m tall, armed with barbed, stinging, and dendritic hairs — a characteristic shared with other Loasaceae. The leaves are short-petiolate, elliptic, 2–7.5 cm long, with densely dendritic-trichomed lower surfaces and sinuate-toothed to pinnately lobed margins; upper leaves are subsessile and lanceolate. The inflorescences are strongly congested cymes 1–4 cm across, appearing conspicuously white from a dense covering of trichomes. Flowers are about 1 cm long at anthesis, with persistent, linear, plumose petals in yellowish tones, five stamens opposite the sepals with distinctive inflated yellow connectives extending well past the anthers, and a 3-carpellate pistil with a short style and conical stigma. The fruit is an achene roughly 1.5–2 cm long including persistent floral parts, containing a single subapical seed with non-sculptured testa and no endosperm. The chromosome base number is X = 7.
Etymology
The genus Cevallia was described by Spanish botanist Mariano Lagasca y Segura in 1805. The name likely honors Pedro Cevallos Guerra (1764–1840), a prominent Spanish statesman and diplomat who served as Spain's Secretary of State and was a contemporary of Lagasca. The specific epithet sinuata refers to the sinuate (wavy-margined) leaves.
Distribution
Cevallia sinuata is native to northern Mexico (including the state of Hidalgo) and the south-central United States, ranging from Arizona east to Oklahoma. It occupies arid and semi-arid habitats typical of the Chihuahuan and Sonoran Desert borderlands.
Ecology
Cevallia sinuata is adapted to arid environments of the southwestern US–northern Mexico borderlands. Like other members of the Loasaceae, it bears barbed and stinging trichomes that deter herbivory, giving rise to the common name "stinging serpent." The congested, white-appearing cymes and persistent floral parts are characteristic of wind- or generalist-insect pollination strategies common in desert-edge flora. The single-seeded achene with non-sculptured testa and lack of endosperm suggests a dry, dispersal-by-attachment strategy facilitated by the persistent plumose calyx and petals.
Taxonomy
Cevallia is a monotypic genus in the family Loasaceae (order Cornales), with the single accepted species Cevallia sinuata Lag. Two historical synonyms exist: Cevallia albicans Gand. and Petalanthera hispida Nutt., both now considered heterotypic synonyms of C. sinuata. The genus was first described by Mariano Lagasca in 1805 (Variedades de Ciencias, Literatura y Artes 2(4): 36). The chromosome base number is X = 7. The most recent comprehensive treatment is Christy (1998) in the Journal of the Arizona–Nevada Academy of Science.
