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Abstract Detail


Morin, Nancy [1], Ayers, Tina [2], Neff, Lois [3].

Taxonomic discoveries in Nemacladus (Campanulaceae, Nemacladoideae).

Nemacladus, one of two genera in Nemacladoideae, Campanulaceae. consists of 24 species of small annuals, most of which occur in southwestern deserts. Unusual in Campanulaceae, the genus includes species with resupinate and non-resupinate flowers, corollas with petals free to base or connate part of their length, and superior, partially inferior, or nearly entirely inferior ovaries. Species with petals free to base have straight pedicels, are non-resupinate, bilabiate, and have large, conspicuous cells attached to two of the filaments. Species with petals partially connate may be resupinate or not, bilabiate, fan-shaped, or nearly radially symmetric, and generally have sigmoid pedicels and smaller, less conspicuous cells on the filaments. Most plants with small white corollas and sigmoid pedicels were initially placed in N. gracilis. G. T. Robbins named N. secundiflorus (large tubular flowers) and N. sigmoideus (everything else not N. gracilis). Recent work has found three species with small or large, cup-shaped corollas and pigmented filaments within this complex; these are being separated from N. sigmoideus, which is thus restricted to plants with small tubular corollas and unpigmented or pale filaments; a fourth species is intermediate between the widespread, non-resupinate N. orientalis and N. sigmoideus. The new species have distinctive geographical distributions. In addition, notable disjunctions have been identified: Nemacladus secundiflorus, with secund flowers and a distribution in the south coast range of California is shown to differ considerably morphologically from the non-secund populations in the southern Sierra Nevada. A highly disjunct population of Nemacladus twisselmannii, a miniscule plant formerly known from only two small populations on the Greenhorn Plateau of the southern Sierra Nevada, was found in the Anza Borrego Desert. The challenges of studying Nemacladus include difficulty of seeing the plants in the field, loss of most useful characters when plants are pressed, and that two or more species may occur together, flowering at the same time or at different stages of maturity, resulting in many mixed collections. Almost certainly there are more species to be discovered in this genus.

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1 - Flora Of North America, P. O. Box 716, Point Arena, CA, 95468, United States
2 - Northern Arizona University, Biological Sciences, 617 South Beaver Street, Flagstaff, AZ, 86011, United States
3 - 6185 Black Bill Rd, Flagstaff, AZ, 86004, United States

southwestern flora.

Presentation Type: Oral Paper
Session: SYS3, Systematics III: Asterids part 2
Location: Tucson G/Starr Pass
Date: Wednesday, July 31st, 2019
Time: 2:45 PM
Number: SYS3006
Abstract ID:443
Candidate for Awards:None

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