Boykinia

Nuttall

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.
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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.

Distribution

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

Discussion

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

None.

Key

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