Hexastylis virginica
Hexastylis
Virginia ginger, Virginia heartleaf
heartleaf
internodes short, leaves crowded at rhizome apex.
blade variegate or not, cordate, subcordate, or subreniform.
blade membranous or leathery, glabrous.
terminal on rhizome, solitary flowers, subtended by triangular bract.
calyx tube cylindric to narrowly cylindric-urceolate, sometimes with prominent transverse ridge just below sinuses, 8-15 × 6-12 mm, inner surface with high reticulations, lobes erect or weakly spreading, 2-4 × 7-9 mm, adaxially puberulent;
stamen connective not extending beyond pollen sacs;
ovary ca. 1/3-inferior;
ovules 8 per locule;
styles notched at apex.
sepals connate for most of length, usually mixture of brown, purple, or yellow, externally glabrous, inner surface glabrous, with weak to strong network of ridges, calyx tube never forming differentiated utricle or syrinx;
vestigial petals absent;
stamens 12, distinct;
filaments shorter than pollen sacs;
terminal appendage of anther absent or rudimentary;
ovary superior or partly inferior, 6-locular;
styles 6, distinct (except sometimes at extreme base).
fleshy, dehiscence irregular.
ovoid, not winged, with fleshy appendage.
= 13.
= 26.
Hexastylis virginica
Hexastylis
Plants of Hexastylis virginica with small, cylindric-urceolate calices have been treated as a distinct species, H. memmingeri. The two calyx types are often found in the same population, however, so H. memmingeri seems unworthy of taxonomic recognition at any rank.
Prior to the study by H. L. Blomquist (1957), many botanists interpreted Hexastylis virginica in a very broad sense, so old herbarium specimens of many other species of Hexastylis are often annotated as H. virginica.
The Cherokee used Hexastylis virginica medicinally to stop blood from passing (D. E. Moerman 1986, as Asarum virginicum).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 10 (all in the flora).
Hexastylis is very similar to the Asiatic genera Heterotropa C. Morren & Decaisne and Asiasarum F. Maekawa; a strong case could be made for combining the three genera. Nevertheless, all three of these genera seem distinct from Asarum (in which they have been included by some authors; e.g., K. Barringer 1993) in their connate sepals, distinct styles, nonappendiculate anthers, and superior or partly inferior ovaries.
Herbarium specimens of Hexastylis are difficult to work with. The form of the calyx is very important taxonomically, but the calyx is fleshy and brittle and does not press well. Allowing flowers to wilt for several hours before pressing may help to reduce distortion, because the calyx becomes more flexible and less likely to split in the press. Features of the inner surface of the calyx are also important, but collectors seldom cut open flowers and press them with the inside visible. For this reason, herbarium specimens of Hexastylis are difficult to identify reliably, and meaningful work on the group requires field studies. L. L. Gaddy (1987) and H. L. Blomquist (1957) gave photographs and drawings of flowers of all species, and an extensive collection of liquid-preserved flowers is housed to the University of Tennessee; these are very helpful in identifying Hexastylis specimens.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Sterile tip of style deeply 2-cleft, sinus reaching stigma; leaf blade triangular to ovate-sagittate or subhastate. | → 2 |
1. Sterile tip of style undivided or shallowly 2-cleft, sinus not reaching stigma; leaf blade cordate to orbiculate, triangular-cordate, or subreniform. | → 3 |
2. Calyx not abruptly contracted near middle, urceolate-campanulate or ovoid, tube smooth internally, lobes erect or spreading. | H. arifolia |
2. Calyx abruptly contracted near middle, proximally narrowly cup-shaped, distally broadly cylindric, tube reticulately ridged internally, lobes spreading. | H. speciosa |
3. Inner surface of calyx lobes pilose; rhizomes dimorphic, internodes of flowering rhizomes short, leaves crowded at rhizome apex, internodes of sterile rhizomes often long, leaves scattered along length of rhizome. | H. lewisii |
3. Inner surface of calyx lobes puberulent; rhizomes not dimorphic, internodes short, leaves crowded at rhizome apex. | → 4 |
4. Calyx tube broadly urceolate-campanulate or rhombic-ovoid, conspicuously tapered above middle. | → 5 |
4. Calyx tube cylindric to narrowly cylindric-urceolate, not much tapered above middle. | → 7 |
5. Calyx tube urceolate-campanulate; calyx lobes 10–22 mm wide. | H. shuttleworthii |
5. Calyx tube rhombic-ovoid; calyx lobes 3–8 mm wide. | → 6 |
6. Internal reticulations of calyx tube well developed, ridges 1.5–2 mm high; ovary superior. | H. rhombiformis |
6. Internal reticulations of calyx tube absent or poorly developed, ridges 0–1 mm high; ovary ca. 1/3-inferior. | H. contracta |
7. Calyx lobes erect or weakly spreading, 2–4 mm; calyx tube cylindric to narrowly cylindric-urceolate. | H. virginica |
7. Calyx lobes moderately spreading to reflexed, 4–15 mm; calyx tube cylindric. | → 8 |
8. Calyx tube wider than long, its opening wider than length of lobes. | H. minor |
8. Calyx tube at least as long as wide, its opening narrower than length of lobes. | → 9 |
9. Calyx tube 4–7 mm wide, lobes 4–7 mm wide. | H. naniflora |
9. Calyx tube 7–14 mm wide, lobes 6–17 mm wide. | H. heterophylla |
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