Styrax platanifolius subsp. texanus

(Cory) P. W. Fritsch

Ann. Missouri Bot. Gard. 84: 744. 1998 ,.

Common names: Texas snowbell
Basionym: Styrax texanus Cory Madroño 7: 112. 1943 (as texana)
Synonyms: Styrax platanifolius var. texanus (Cory) B. L. Turner
Treatment appears in FNA Volume 8. Treatment on page 344. Mentioned on page 343, 345.

Young twigs faintly glaucous, glabrous except for scattered, orangebrown or dark-brown, stalked, stellate hairs proximally. Leaf-blades: margins often weakly undulate, usually entire, rarely 3-lobed or coarsely toothed, abaxial surface with white stellate-tomentose pubescence in addition to scattered, orangebrown or dark-brown, stalked, stellate hairs on some leaves, surface completely covered and obscured by pubescence, adaxial surface glabrous. Pedicels white stellate-tomentose. Flowers: calyx thinly and evenly white stellate-tomentose, margins and teeth densely glandular, at least some teeth to 1 mm; style pubescent from proximal end to 15–35% of total length.


Phenology: Flowering Apr–May; fruiting Jul–Sep.
Habitat: Limestone cliffs, ledges, or cobble, intermittent drainages
Elevation: 500-700 m

Discussion

Of conservation concern.

Subspecies texanus has the narrowest distribution of the five subspecies of Styrax platanifolius, with documented localities in Edwards, Real, and Val Verde counties, and one population reported in Del Rio County. It is probably also the rarest of the subspecies, with fewer than 20 populations known. Only four of those populations consist of more than 25 individuals (J. M. Poole, pers. comm.). Although seed production and the germination rate of subsp. texanus are relatively high, grazing by both native and exotic herbivores has prevented regeneration within populations (P. A. Cox bis 1987; Poole, pers. comm.).

Young plants of subsp. texanus often have sparsely pubescent leaves abaxially, the tomentum developing with age.

Subspecies texanus is in the Center for Plant Conservation’s National Collection of Endangered Plants as Styrax texanus.

Selected References

None.

Lower Taxa

None.

"lengthofcorolla" is not declared as a valid unit of measurement for this property."-2.3timesaslongascalyx" is not declared as a valid unit of measurement for this property.

nearly +  and distinct +
perigynous;epigynous +
Peter W. Fritsch +
(Cory) P. W. Fritsch +
Styrax texanus +
indistinct +
9 cm90 mm <br />0.09 m <br /> (12 cm120 mm <br />0.12 m <br />) +
9 cm90 mm <br />0.09 m <br /> (11.5 cm115 mm <br />0.115 m <br />) +
4.5 cm45 mm <br />0.045 m <br /> (9 cm90 mm <br />0.09 m <br />) +
ovate;depressed-orbiculate +
4.2 cm42 mm <br />0.042 m <br /> (9 cm90 mm <br />0.09 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
stellate-tomentose +
0.45 cm4.5 mm <br />0.0045 m <br /> (0.55 cm5.5 mm <br />0.0055 m <br />) +
grayish white +
0.7 cm7 mm <br />0.007 m <br /> (1 cm10 mm <br />0.01 m <br />) +
stellate-pubescent +
0.7 cm7 mm <br />0.007 m <br /> (1.1 cm11 mm <br />0.011 m <br />) +
Texas snowbell +
subinduplicate-valvate +  and imbricate +
1.2 cm12 mm <br />0.012 m <br /> (2.1 cm21 mm <br />0.021 m <br />) +
500-700 m +
curved +  and straight +
solitary +  and 2-7-flowered +
2 cm20 mm <br />0.02 m <br /> (5 cm50 mm <br />0.05 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
not winged +, nutlike +, 3-valved +  and capsular +
loculicidal +
ellipsoid;globose +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
Limestone cliffs, ledges, or cobble, intermittent drainages +
in-addition-to-scattered +  and scattered +
pubescence +
dark-brown +, orangebrown +  and white +
stellate-tomentose +
conspicuous +
5 (?) +  and 6 (?) +
0.3 cm3 mm <br />0.003 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
0 cm0 mm <br />0 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
entire +  and serrate +
toothed +, 3-lobed +, entire +  and undulate +
stellate-tomentose +
0.4 cm4 mm <br />0.004 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
perigynous;epigynous +
0.6 cm6 mm <br />0.006 m <br /> (2 cm20 mm <br />0.02 m <br />) +
Flowering Apr–May +  and fruiting Jul–Sep. +
connate +, distinct +  and free +
Ann. Missouri Bot. Gard. +
ellipsoid;globose +
2(-4) times number of corolla lobes +
2-4[-5]-lobed +  and truncate +
in-addition-to-scattered +
dark-brown +, orangebrown +  and white +
stellate-tomentose +
Styrax platanifolius var. texanus +
Styrax platanifolius subsp. texanus +
Styrax platanifolius +
subspecies +
0 cm0 mm <br />0 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
glabrous +  and glaucous +
shrub +  and not suckering +