Geographic variation in the frequencies of trichome phenotypes of Datura wrightii and correlation with annual water deficit
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| Authors: | Hare, JD; Elle, E |
| Year: | 2001 |
| Journal: | Madrono 48: 33-37 |
| Title: | Geographic variation in the frequencies of trichome phenotypes of Datura wrightii and correlation with annual water deficit |
| Abstract: | The perennial plant species, Datura wrightii Regel (Solanaceae) is dimorphic for leaf trichome type. Some plants produce almost exclusively short, non-glandular trichomes, while other plants within the same population produce almost exclusively longer, glandular trichomes. In a previous survey of 19 southern California populations, the frequency of plants producing glandular trichomes ranged from 0-82%, and plants with glandular trichomes were absent from desert populations. Here we expand our studies to a total of 56 D. wrightii populations from central and southern California. We also examined the relationship between the frequency of glandular trichomes and two factors that broadly determine the availability of water at each site. The first was mean annual rainfall, while the second was mean annual evapotranspiration rate. The frequency of plants with glandular trichomes increased with increasing mean rainfall and decreased with increasing mean annual evapotranspiration rate. Combined, these two environmental variables accounted for about one-third of the variation in the proportion of plants with glandular trichomes. Results suggest that the production of a water-based exudate by plants with glandular trichomes may impose an additional demand for water on those plants compared to plants with non-glandular trichomes. Because of this additional water demand, the frequency of plants with glandular trichomes may decline relative to that of plants with non-glandular trichomes as available water becomes more limiting. |
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