Herbs, annual; hemiparasitic. Stems erect, not fleshy, glabrous or villous to scabrid. Leaves cauline, opposite; petiole absent; blade not fleshy, not leathery, margins entire, irregularly lobed, pinnatifid, or 2-pinnatifid. Inflorescences axillary, flowers 2 per axil; bracts present. Pedicels present; bracteoles absent. Flowers: sepals 5, calyx +/- radially symmetric, campanulate, lobes linear to lanceolate; petals 5, corolla yellow often with red, maroon, or purple markings in throat, bilabiate, campanulate with spreading lobes, abaxial lobes 3, adaxial 2; stamens 4, equal to subequal, filaments hairy proximally, glabrous or tomentose to lanate distally, anthers glabrous; staminode 0; ovary 2-locular, placentation axile; stigma simple. Capsules: dehiscence loculicidal. Seeds 30–40, brown, globular-ovoid or irregular, wings present or absent. x = 13.

Distribution

s United States, Mexico, West Indies.

Discussion

Species 17 (5 in the flora).

The phylogenetic position of Seymeria remains unclear. N. D. Young et al. (1999) placed Seymeria in an unresolved clade with Agalinis and Macranthera, among other genera. M. C. Neel and M. P. Cummings (2004) recovered a clade including Aureolaria, Brachystigma, Dasistoma, and Seymeria. A. D. Wolfe et al. (2005) placed Seymeria sister to Agalinis. J. R. Bennett and S. Mathews (2006) found that Seymeria is in a clade including Agalinis and Aureolaria, and also Esterhazya J. G. Mikan.

Seymeria is one of the few North American root-parasitic genera of economic importance in that S. cassioides is a parasite of pine species used for lumber in the southeastern United States (L. J. Musselman 1996).

The common name blacksenna is derived from the superficial resemblance to Senna (Fabaceae).

Selected References

Pennell, F. W. 1925. The genus Afzelia: A taxonomic study in evolution. Proc. Acad. Nat. Sci. Philadelphia 77: 335–373.

Turner, B. L. 1982. Revisional treatment of the Mexican species of Seymeria. Phytologia 51: 403–423.

Lower Taxa

Seymeria bipinnatisecta, Seymeria cassioides, Seymeria falcata, Seymeria pectinata, Seymeria scabra

Key

1	Corollas externally pubescent or tomentose.	> 2
2	Filaments tomentose to lanate distally, anthers dehiscing to 1/4 lengths; capsules densely tomentose or pubescent to glabrescent; seeds: wings present.	Seymeria pectinata
2	Filaments glabrous distally, anthers dehiscing 1/2+ lengths; capsules pubescent; seeds: wings absent.	Seymeria bipinnatisecta
1	Corollas externally glabrous.	> 3
3	Leaves: blade margins 2-pinnatifid, pinnules filiform, surfaces not scabrid; capsules pyriform.	Seymeria cassioides
3	Leaves: blade margins entire, 3-lobed, irregularly pinnatifid, or slightly 2-pinnatifid, pinnules linear to lanceolate, surfaces scabrid; capsules +/- falcate.	> 4
4	Leaves: blade margins entire, 3-lobed, or irregularly pinnatifid, surfaces minutely scabrid; pedicels 6–10 mm; capsules glabrous.	Seymeria falcata
4	Leaves: blade margins pinnatifid or slightly 2-pinnatifid, surfaces strongly scabrid; pedicels 1.5–4 mm; capsules glandular-pubescent.	Seymeria scabra