HYBANTHUS PENNELLII (VIOLACEAE) RAISED TO SPECIFIC RANK:
A GYPSOPHILE FROM NUEVO LEON, MEXICO

Billie L. Turner
Plant Resources Center
The University of Texas

Austin, TX 78712

ABSTRACT

Hybanthus potosinus var. pennellii is elevated to specific rank as Hybanthus peeneilii (C.V.
Morton) B.L. Turner, comb, et stat. nov. It is a localized gypsophilic endemic of Nuevo Leon, most
closely related to H. potosinus of San Luis Potosi but imph <VtinU Its ■ J ilinicship to the latter is

briefly discussed and a map showing their distribution is provided.

KEY WORDS: Hybanthus, H. pennellii, H. potosinus, gypsophile, Nuevo Leon, Mexico

Routine identification of Mexican plants from Nuevo Leon has brought to focus the following
gypsophile, previously identified as Hybanthus potosinus var. pennellii Morton, herein elevated to
specific rank. Morton, in his original publication, gave only a brief description of his novelty, noting
that it differed "from the typical variety in its acutish leaves, acuminate calyx lobes, and somewhat
larger flowers, the labellum being 10 mm. long and 6 mm broad." Because of his limited description
of var. pennellii, I provide the following more inclusive description, this based upon the two Hinton
sheets cited below.

HYBANTHUS PENNELLII (C.V. Morton) B.L. Turner, comb, et stat. nov. Based upon

Hybanthus potosinus C.V. Morton var. pennellii C.V. Morton, Contr. U.S. Natl. Herb. 29: 80.
1944. TYPE: MEXICO. Nuevo Leon. Mpio. Galeana, Alamar, Pab[l]illo, 2-3 Jul 1934,
F.W. Pennell 17231 (holotype: US digital image!).

Perennial herbs, 10-30 cm high. Stems simple, arising from slender rhizomes, beset with
stiff spreading hairs ca 1 mm long. Leaves (at mid-stem) 3-5 cm long, 1.5-2.8 cm wide; petioles 1-3
mm long; blades elliptic to broadly obovate, appressed-pilose on both surfaces, mainly along the
venation, margins weakly dentate to serrulate, the apices acute to obtuse. Stipules lanceolate, ca 3
mm long. Flowers axillary, the pedicels mostly 10-15 mm long. Calyx lobes lanceolate, ca 3 mm
long, pubescent like the stems. Petals 5, the laterals purple, ca 3 mm long, their apices acute,
reflexed; labellum ca 10 mm long, claw ca 4 mm long, the blades flabellate, ca 6 mm long, 7 mm
wide, purplish-white, sparingly pubescent apicalh, Capsules ellipsoid, ca 5 mm long, 2.5 mm wide,
glabrous; seeds 5-6, globose, glabrous, ca 1.5 mm across.

SPECIMENS EXAMINED. MEXICO. Nuevo Leon. Mpio. Galeana: La Poza to Rio de Jose,
1690 m, gypsum hillside, 25 Jul 1995, Hinton et al. 25372 (TEX): E of Pablillo, 2108 m, gypsum
hillside, 30 Oct 2009, Hinton et al. 29053 (TEX).

The following key distinguishes the two taxa concerned:

1. Leaves (at mid-stem) 2.0-2.5 cm long; stipules ca 1.2 mm long; pedicels mostly ca 5 mm long;

labellum ca 7 mm long; San Luis Potosi Hybanthus potosinus

1. Leaves (at mid-stem) 3-5 cm long; stipules ca 3 mm long; pedicels mostly 10-15 mm long;
labellum ca 10 mm long; Nuevo Leon Hybanthus pennellii

Turner: HybanthuspenneSii, Mexican gypsophile

Pennell (1886-1952), an expert on the family Scrophulariaceae, made his first collections in
Mexico during the year 1934 (Camp 1952), obtaining Hybantkus pennellii from the vicinity of
Pablillo, perhaps unaware of its gypseous substrate (this not recorded on his collection label). To my
knowledge, there have been only two additional collections of the taxon, both by the Hintons and
both from near the type locality. Distribution of the two taxa is shown in Fig. 1. The specific locality
for the type of H. potosinus was obtained from Sanchez (1 969).

ACKNOWLEDGEMENTS

I am grateful to Guy Nesom for reviewing the paper. A hi -res photograph of an isotype (NY)
of Rfoctnthus potosinus was obtained fromthewebsiteJSTOR.org; an image oftheholotypeis on the
US website.

LITERATURE CITED

Camp, W.H. 1952. Francis Whittier Pennell. Taxon 1:83.

Morton, C.V. 1944. The genus Hybantkus in Continental North America. Contr. U. S. Natl. Herb.

29: 74-82.
Sanchez, M.S. 1969. Las colecciones botanicas de C.A Purpus en Mexico. Univ. Calif. Publ. Bot.

HYBANTHUS
• pennellii
o potosinus

Figure 1. Distribution of Hybantkus pennellii andH. potosinus.