Journal of the Plant Resources Center of the University of Texas at Austin
Number 10 — December 2007
[Published: 23 November 2007]


Contents:

Two New Species of Malvaceae from Sonora, Mexico and Texas
Paul A. Fryxell View Abstract — Download article (875 KB)

Distribution of Heliotropium torreyi (Boraginaceae), and the Description of a New Species from Its Midst
Billie L. Turner View Abstract — Download article (8.7 MB)

Phaseolus texensis (Leguminosae: Phaseolinae): A New Species from the Edwards Plateau of Central Texas
Alfonso Delgado-Salinas and William R. Carr View Abstract — Download article (5.8 MB)

A Field Study of Hybridization between Berberis swaseyi and B. trifoliolata (Berberidaceae) in Hays County, Texas
Robert T. Harms View Abstract — Download article (14.4 MB)

Pollen Morphology and Ultrastructure of Calyceraceae
Melanie L. DeVore, Zaiming Zhao, Robert K. Jansen, and John J. Skvarla View Abstract — Download article (17.4 MB)

The Asteraceae of Northwestern Pico Zunil, a Cloud Forest in Western Guatemala
Taylor Sultan Quedensley and Thomas B. Bragg View Abstract — Download article (2.9 MB)

Abstracts

Two New Species of Malvaceae from Sonora, Mexico and Texas
Paul A. Fryxell
1—6

Abstract: Batesimalva stipulata is described from Sonora, Mexico (Mpio. de Alamos) and Wissadula parvifolia from Texas (Hidalgo County). The positions of both species in their respective genera are discussed, and keys are provided for the distinction of the new species from their congeners.

Resumen: Se describen Batesimalva stipulata de Sonora, México (Mpio. de Alamos) y Wissadula parvifolia de Texas (Hidalgo County). Las colocaciónes de las dos especies en sus propios géneros son discutidos, y se presentan claves para distinguir las especies nuevas de otras especies relacionadas.

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Distribution of Heliotropium torreyi (Boraginaceae), and the Description of a New Species from Its Midst
Billie L. Turner
7—10

Abstract: The taxonomic history and geographical distribution of Heliotropium torreyi is reviewed. From amongst its fabric a new taxon was discerned and described as H. powelliorum. While allopatric with H. torreyi, the two taxa do not intergrade, suggesting that specific status is warranted. An illustration of the novelty is provided, along with a map showing its distribution, and that of its closest relative, H. torreyi.
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Phaseolus texensis (Leguminosae: Phaseolinae): A New Species from the Edwards Plateau of Central Texas
Alfonso Delgado-Salinas and William R. Carr
11—17

Abstract: Phaseolus texensis is a new species known only from rocky canyons of the eastern and southern Edwards Plateau of central Texas. Morphological examination and field observations, in conjunction with current molecular phylogenetic analyses based on nuclear ribosomal and chloroplast DNA sequences and a discrete and limited geographical range, support the taxonomic recognition of this species, which is accordingly described and illustrated here.

Resumen: La especie Phaseolus texensis es dada a conocer como restringida a cañones pedregosos de las partes orientales y meridionales de la región conocida como Edwards Plateau, de la porción central del estado de Texas, Estados Unidos de América. Un examen morfológico y observaciones en campo, aunados a estudios filogenéticos moleculares basados en secuencias de ADN nuclear ribosomal y de cloroplastos y a una restringida distribución garantizan el reconocimiento de esta especie y por lo tanto, aquí se describe e ilustra.

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A Field Study of Hybridization between Berberis swaseyi and B. trifoliolata (Berberidaceae) in Hays County, Texas
Robert T. Harms
18—31

Abstract: The widespread Berberis trifoliolata is sympatric with the narrowly restricted B. swaseyi in central Texas, where apparent intermediates occur. A detailed field study of sympatric populations in northern Hays Co. during 2004 to 2007 clarifies the morphological and phenological differences between the two species and shows that intermediates almost surely arose from hybridization. Limited evidence of introgression is also discussed.
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Pollen Morphology and Ultrastructure of Calyceraceae
Melanie L. DeVore, Zaiming Zhao, Robert K. Jansen, and John J. Skvarla
32—48

Abstract: Pollen morphology of 13 species from all six genera of Calyceraceae (Acicarpha, Boopis, Calycera, Gamocarpha, Moschopsis, and Nastanthus) and representatives of the Campanulaceae and Goodeniaceae is examined with light (LM), scanning (SEM), and transmission (TEM) electron microscopy. Acicarpha, Calycera, and Nastanthus pollen grains are distinguished by angulaperturate apertures, colpar ledges and surface depressions between colpi known as intercolpar concavities (IC). Pollen of Gamocarpha and Moschopsis is tricolporate rather than angulaperturate and without an IC. Some species of Boopis are similar to the preceding genera (e.g., B. graminea), while others (e.g., B. gracilis) are angulaperturate with ICs. Structural features derived from fractured pollen in SEM and sections in TEM show pollen walls composed of prominent columellae ca. 0.55-1.1 μm high and < 0.25 μm wide. The columellae terminate distally into a complex of shortened columellae ca. 1.5 μm in length and are separated by an ill-defined irregular internal tectum layer. This structural complex is well known in several tribes of the Asteraceae and referred to as the Anthemoid type. In those grains with an IC, the structure consists of essentially short (ca. 1 μm), unbranched columellae, similar to those found within the Asteraceae subfamily Barnadesioideae (Dasyphyllum and Schlechtendalia). Goodeniaceae (including Brunonia) pollen has angulaperturate apertures, spinules (i.e., minute spines), problematic IC and some structural similarity to Calyceraceae pollen. The tendency within Calyceraceae to develop colpar ledges, ektexine bridges, and ICs may be a synapomorphy uniting the family with Goodeniaceae. If the ancestral pollen type for the Calyceraceae, Asteraceae, and Goodeniaceae clade is the Gamocarpha type (convex intercolpar regions; no colpar ledges and no ektexine bridges), then the appearance of these structures within each family may be a synapomorphy supporting their close phylogenetic relationship suggested by molecular analyses.
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The Asteraceae of Northwestern Pico Zunil, a Cloud Forest in Western Guatemala
Taylor Sultan Quedensley and Thomas B. Bragg
49—70

Abstract: From 2003 to 2005, 46 genera and 96 species of native Asteraceae were collected on the northwestern slopes of Pico Zunil, a montane cloud forest habitat in southwestern Guatemala. Combining the present survey with past collections, a total of 56 genera and 126 species of Asteraceae have been reported from Pico Zunil, five of which are naturalized Old World species. In the present study, the Heliantheae contains the greatest number of native species (29). The most diverse genus is Ageratina (Eupatorieae, 9 species). Species richness of native Asteraceae measured along an elevational gradient ranged from a low of 16 species at 3400-3542 m to a high of 68 species at 2300-2699 m, where human land use most actively affects cloud forest habitat. Of the plants collected, Ageratina rivalis and Verbesina sousae were new species records for Guatemala. Six more species were new records for the Department of Quetzaltenango: Ageratina pichinchensis, A. prunellaefolia, A. saxorum, Koanophyllon coulteri, Stevia triflora, and Telanthophora cobanensis. In addition, 16 of the 96 native species collected are known only from to the western montane departments of Guatemala and the montane regions of southern Chiapas, Mexico. We provide a base of information against which future studies can measure temporal changes in presence of species such as may accompany environmental changes resulting from human activities and/or climate change.
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