[PCA] Pollinators Complicate Conservation of an Endemic Plant: Physaria obcordata (Cruciferae) in the Piceance Basin, Colorado

[Patricia_DeAngelis at fws.gov]

A nice example of taking a more comprehensive look at management and 
conservation potential for plants, pollinators, dispersers, etc. and 
making the distinction between floral visitors and pollinators...Take note 
of the endearing Dedication on this article!

Pollinators Complicate Conservation of an Endemic Plant: Physaria 
obcordata
(Cruciferae) in the Piceance Basin, Colorado
Author(s): Vincent J. Tepedino, William R. Bowlin Terry L. Griswold
Source: Natural Areas Journal, 32(2):140-148. 2012.
Published By: Natural Areas Association
URL: http://www.bioone.org/doi/full/10.3375/043.032.0202

ABSTRACT: 
Physaria obcordata is a rare endemic of western Colorado. Plants are 
self-incompatible; they cannot reproduce sexually unless pollinators move 
pollen between flowers of different genets. We found no evidence that: 
seed production was limited by inadequate pollination or that pollinations 
between near neighbor plants (inbreeding depression) or between distant 
plants (outbreeding depression) resulted in reduced fruit or seed set. 
Examples are given of the potentially devastating effect of grazing on 
fruit and seed production. Preliminary evidence suggests that P. obcordata 
can hybridize with its common congener, P. acutifolia. Only crosses with 
P. obcordata as pollen recipient and P. acutifolia as pollen donor seemed 
fertile. Primary flower-visitors of P. obcordata are ground-nesting native 
bees in the families Andrenidae and Halictidae. Most species visiting the 
flowers of P. obcordata are generalists. Only two bee species were likely 
mustard specialists. The only non-bee visitor of any import was a 
dipteran, Gonia (Tachinidae). Predictions of the distances flown by common 
bee visitors were made using the equations of Greenleaf et al. (2007). No 
bee is likely to travel more than 1 km from its nesting site to visit P. 
obcordata flowers and most are likely to fly distances that are 
significantly less. The implications of flight range estimates for gene 
flow between Physaria populations and for pollinator protection are 
discussed. Several recommendations are made for conservation of P. 
obcordata and its attendant bees.


Patricia S. De Angelis, Ph.D.
Botanist, Division of Scientific Authority-US Fish & Wildlife 
Service-International Affairs
Chair, Medicinal Plant Working Group-Plant Conservation Alliance
4401 N. Fairfax Dr., Suite 110
Arlington, VA  22203
703-358-1708 x1753
FAX: 703-358-2276

Promoting sustainable use and conservation of our native medicinal plants. 

<www.nps.gov/plants/medicinal>

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