Volume 80 - Issue 1 (March 2015)

Floral Phenology and Sex Ratio of Piratebush (Buckleya distichophylla), a Rare Dioecious Shrub Endemic to the Southern Appalachian Mountains

ABSTRACT Piratebush (Buckleya distichophylla, Santalaceae) is a rare dioecious and hemiparasitic shrub endemic to the Appalachian Mountains of Virginia, North Carolina, and Tennessee. Previous studies on piratebush suggest sexual reproductive deficiency as a possible explanation for the rare and scattered distribution of piratebush and a concern for subsequent population decline. To further investigate the reproductive biology of piratebush, we examined sex ratio and flowering phenology in the densest population of piratebush, found on Poor Mountain in southwest Virginia. Sex ratio data were collected through field surveys along ecological transects. Results show a male-biased sex ratio (61:39) of flowering individuals, with 15% nonflowering. Size data confirm significantly smaller size for nonflowering individuals (p < 0.01), suggesting combined characteristics of size and nonflowering as an indicator of juvenility. Floral phenology data were recorded from 23 males and 20 females in varied representative elevation and aspect gradients. Flower abundance was male-dominant by >24:1.

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Reproductive Biology of the Endangered Schweinitz’s Sunflower (Helianthus schweinitzii)

ABSTRACT The federally endangered Schweinitz’s sunflower (Helianthus schweinitzii) is endemic to the Carolina Piedmont. This study investigates the reproductive biology of this sunflower to better understand the two main methods of propagation: sexual reproduction by seed and asexual reproduction by tuberous rhizome. The researchers randomly collected the mature and senescent heads (capitula) and recorded the numbers of filled and unfilled cypselae in the fall of 2012. Analyses of the effect of the use of gibberellic acids (GA) and the use of a mix of charred soil and aboveground organic matter on seed germination were conducted. The GA treatment at 1,000 mg L1 significantly increased germination. Cypselae planted in a mix of soil and aboveground matter that had been burned for 30 min germinated significantly better compared to a control group. To study asexual reproduction, tuberous rhizomes were collected and the effect of a cold treatment was tested as a second

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