J. Acad. Nat. Sci. Philadelphia 7: 113. 1834, name conserved ,.

Etymology: For Samuel Boykin, 1786–1848, planter, physician, and naturalist of Milledgeville, Georgia
Treatment appears in FNA Volume 8. Treatment on page 125. Mentioned on page 45, 47, 120, 124, 132.

Herbs, rhizomatous, not stoloniferous (± stoloniferous in B. intermedia). Flowering stems erect, leafy, 10–130 cm, densely stipitate-glandular and eglandular-pubescent. Leaves in basal rosette and cauline; cauline leaves similar to basal, gradually reduced distally to sessile bracts; stipules present; petiole densely stipitate-glandular; basal leaf blades reniform to reniform-orbiculate or cordate, shallowly lobed to deeply cleft, base cordate, ultimate margins crenate to serrate, apex acute or rounded, surfaces stipitate-glandular, adaxial surface grooved over veins; venation palmate. Inflorescences compound, dichasial cymes, terminal from terminal bud in rosette, branches (3–)5–20(–30)-flowered, bracteate. Flowers ± radially symmetric; hypanthium adnate 1/2–5/6 to ovary, free from ovary 0.7–3 mm, usually green, sometimes purple; sepals 5, green to purple; petals 5, white (sometimes with pink veins in B. richardsonii); nectary tissue encircling base of styles at junction of ovary and free hypanthium; stamens 5; filaments linear to subulate; (anthers apiculate or obtuse); ovary 2/3 to completely inferior, 2-locular, carpels connate proximally; placentation axile; styles 2; stigmas 2. Capsules 2-beaked. Seeds (ca. 50–500), usually black, (brown in B. richardsonii), ellipsoid, tuberculate (smooth in B. richardsonii). x = 7.


North America, nw Mexico, e Asia (Japan).


Neoboykinia H. Hara; Therofon Rafinesque

Species 7 (6 in the flora).

The Japanese species is Boykinia lycoctonifolia (Maximovicz) Engler, which, based on its morphology, seems to be most closely related to B. aconitifolia.

Selected References



1 Inflorescence branches 3-flowered; seeds smooth. Boykinia richardsonii
1 Inflorescence branches 5-30-flowered; seeds tuberculate > 2
2 Leaf blades usually orbiculate-cordate, sometimes reniform, lobed to 1/2 their lengths; stipules of cauline leaves expansions from petiole base > 3
2 Leaf blades usually reniform, rarely cordate, lobed to 1/2-3/4 their lengths; stipules of cauline leaves foliaceous or expansions from petiole base > 4
3 Petals 2-3 times as long as sepals; basal leaf blades usually 3-9-lobed. Boykinia occidentalis
3 Petals shorter than or to 1.5 times as long as sepals; leaf blades shallowly and indistinctly lobed. Boykinia rotundifolia
4 Hypanthia saucer-shaped; petals suborbiculate to ovate, base contracted to claw, margins undulate. Boykinia major
4 Hypanthia campanulate to turbinate; petals ovate to spatulate, base tapered to claw, margins plane > 5
5 Rhizomes usually underground, not usually stoloniferous; stipules of cauline leaves usually expansions from petiole base, fringed with brown hairs, sometimes foliaceous; nectaries green. Boykinia aconitifolia
5 Rhizomes proliferating above ground, stoloniferous; stipules of cauline leaves usually foliaceous; nectaries greenish yellow. Boykinia intermedia