Malvaceae subfam. byttnerioideae
Hermannia
burstworts, hermannia
hairy, hairs usually stellate, sometimes intermixed with capitate-glandular and subsessile glandular hairs.
blades usually unlobed, rarely lobed (Hermannia), margins serrate, dentate, or entire.
petiolate;
stipules deciduous, foliaceous, narrowly dimidiate-lanceolate or narrowly dimidiate-ovate, triangular, margins simple-bristled;
blade usually unlobed, rarely lobed, margins dentate or staminodes 0;
filaments ligulate, very compressed, adnate to petal base and gynophore or ovary base, distally free, incurved, not abruptly dilated, expanded region narrowly oblong from base to above anther base, apex acuminate or acute, glabrous;
anthers 2-thecate, lanceolate, [1–]2–3.5[–10] mm, inflexed, connivent to style, longitudinally dehiscent; thecae with rim ciliate from simple hairs, apex acuminate, slightly twisted, gland at apex only (H. texana) or also at theca base (H. pauciflora);
gynoecium syncarpous, 5-carpellate, stipitate, 5-angled, locules opposite sepals;
ovary 5-locular;
ovules 4–14 per locule, ascending or horizontal, anatropous or amphitropous;
styles persistent, 5, shortly exserted, presumably connate at anthesis (connate, distinct, or partially distinct dried), filiform;
stigmas inconspicuous, terete and 1-dentate (acute) or filiform and often few-minutely papillate at apex, rarely truncate, inconspicuous.
axillary, terminal, or leaf-opposed, usually antisepalous or absent (Hermannia and Waltheria);
gynoecium syncarpous.
capsules or schizocarps, dehiscence loculicidal or septicidal.
capsules, 5-locular, in apical view 5-angled, 5-lobed, parted between angles, in lateral view emarginate at apex, margins curved, stipitate, valve margins dark-rimmed, dentate, teeth terminated by hairy tubercles not elsewhere on fruit (H. pauciflora) or hairy processes (H. texana), denser on valves, stellate-pubescent.
(1–)5–10, usually glabrous.
0–8 per locule, brown, crescentiform-reniform, chalazal end wider, other end acute, large-pitted;
elaiosome conspicuous, white;
endosperm present;
embryo curved, chlorophyllous;
cotyledons flat, narrowly elliptic or oblong-elliptic.
= 6.
Malvaceae subfam. byttnerioideae
Hermannia
Genera 26, species ca. 650 (4 genera, 16 species in the flora).
Byttnerioideae comprise five tribes previously ascribed to the family Sterculiaceae (B. A. Whitlock et al. 2001). It is sister to Grewioideae; together they represent the earliest branching taxa in the family (C. Bayer et al. 1999; R. Nyffeler et al. 2005).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species ca. 180 (2 in the flora area).
Hermannia is primarily southern African, with other species found scattered outside Africa, notably former Gilesia biniflora F. Mueller from Australia, distinguished by totally free filaments. Only four species are exclusively from the Americas, found in Mexico and across its national borders. One species extends north to Arizona, and one extends north to Texas. Two are found
outside the flora area: H. palmeri Rose from rocky granitic hillsides, sandy mesas, and coastal dunes of Baja California Sur and H. inflata Link & Otto from tropical dry deciduous forests in mountains of southern Mexico and northern Guatemala.
I. C. Verdoorn (1980) placed the only two fringed-capsuled species in southern Africa in subg. Hermannia, the basal subgenus, and she related them to the two American species that are fringed-capsuled: H. texana (Texas and Mexico) and H. palmeri (Baja California Sur). Both species from the flora area would lie also within subg. Hermannia in her key to taxa by possession of “narrowly oblong stamen filaments with the expanded portion of the filaments overlapping the anther bases.”
The coherence of styles and connivance of anthers at anthesis (M. Jenny 1985, 1988), nectaries (S. Vogel 2000), and ovule/seed number per carpel need further study in the field to investigate possible cryptic floral differentiation between plants of Hermannia that would indicate the initial stages of the well-developed floral and pollen distylous dimorphisms of Melochia and Waltheria.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Styles 3.9–5.8 mm; leaf blades olive, with terminal trichome at each tooth apex never simple, rather stellate or stellate-bristled and slightly exserted from stellate trichomes of tooth sides; distal petal lamina densely capitate-glandular abaxially; capsules: endocarp corneous, rigid, valve margins fringed, processes filiform, flexible, 0.9–3.2 mm; trichome rays of terminal trichome of fringe process with trichome rays ascending, fine, and only slightly firmer or slightly longer than trichome rays of hairs below process apex; seeds: elaiosome narrowly transversely rhombic. | H. texana |
1. Styles 1.7–3 mm; leaf blades red to red-rimmed, with terminal trichome at each tooth apex with 1 simple thin seta or seta 2-rayed exserted to 2 times length of stellate trichomes of tooth sides; distal petal lamina subglabrous abaxially; capsules: endocarp chartaceous, slightly sclerified, flexible, valve margins tuberculate, tubercles rigid, 0.2–1.8 mm; terminal trichome of tubercle apex with trichome rays usually planar (spreading); seeds: elaiosome narrowly transversely elliptic. | H. pauciflora |
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