Burstworts [For Paul Hermann, 1646–1695, German-born Dutch botanist and explorer] Burstworts [For Paul Hermann, 1646–1695, German-born Dutch botanist and explorer]

Janice G. Saunders

Subshrubs, [shrubs], prostrate to erect; taprooted. Stems hairy, hairs usually stellate, sometimes intermixed with capitate-glandular and subsessile glandular hairs. Leaves 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. Fruits 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. Seeds 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. x = 6.

Species ca. 180 (2 in the flora area): sw, sc United States, Mexico, Central America (Guatemala), w Asia (Saudi Arabia), Africa, Australia; subtropical and tropical areas.

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.

SELECTED REFERENCE Rose, J. N. 1897. A synopsis of American species of Hermannia. Contr. U.S. Natl. Herb. 5: 130–131.

Lower Taxa

• Hermannia pauciflora S. Watson
• Hermannia texana A. Gray