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1 April 2007 Growth of the rare southern appalachian endemic plant houstonia montana (Rubiaceae) in contrasting habitat types
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We examined the ability of Houstonia montana, a rare plant endemic to the Southern Appalachians, to grow in two markedly different habitat types. Most known populations of H. montana occur on rock outcrops with little soil development and sparse vegetation. In contrast, a few populations occur on grassy slopes with continuous soils and dense surrounding vegetation. We compared growth and life-history traits of two rock-outcrop and two grassy-slope populations. Houstonia montana was a dominant vascular plant species in all four sites, with 20–37 % ground cover on grassy slopes and 4–6% on rock outcrops. Growth began earlier in the season and plants were taller on grassy slopes than on rock outcrops. In contrast, reproductive potential, numbers of leaves, and ratios of leaves:height were markedly higher in one grassy slope site but showed no consistent pattern between habitats. Foliar nitrogen:phosphorus ratios varied widely and indicated N limitation in at least one grassy slope site and P limitation in one rock outcrop site. However, mycorrhizal colonization did not differ between habitat types. Houstonia montana exhibited variation in growth and nutrition across sites that may be unexpected for an apparently stress-tolerant plant. Our results suggest that the ability of H. montana to thrive in grassy sites depends upon rapid early-season growth, and they also raise questions about potentially important genetic variation among populations.
Amy C. Euliss, Melany C. Fisk, S. Coleman McCleneghan and Howard S. Neufeld "Growth of the rare southern appalachian endemic plant houstonia montana (Rubiaceae) in contrasting habitat types 1," The Journal of the Torrey Botanical Society 134(2), (1 April 2007).[177:GOTRSA]2.0.CO;2
Received: 13 November 2005; Accepted: ; Published: 1 April 2007

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