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Hypericum cumulicola (Small) P. Adams (Hypericaceae)
Common Name: Highlands scrub hypericum

Distribution: Hypericum cumulicola is endemic to the Lake Wales Ridge, and only known from Polk and Highlands counties. This species is listed as endangered by the United States Government (USFWS 1999), and the State of Florida (Coile 1998). It was present at only 69 of 254 scrub sites surveyed by Christman (1988). Although some populations of this species can number several thousand plants, most populations are smaller than 1000 plants (median 539 in 34 populations).

Habitats: Almost entirely limited to open sand areas in the xeric Florida rosemary scrub, but also occurs occasionally in adjacent firelines, and less frequently in large openings in well-drained scrubby flatwoods.

Life History: Hypericum cumulicola is a short-lived perennial herbaceous species. Flowering-bearing individuals can reach 20-70 cm in height. It is branched from the base and has a woody/fibrous root system. Stems are shorter and more numerous in winter and spring before reproductive stalks differentiate. During reproductive season, all stems of mature individuals bear flowers and fruits. Leaves are opposite, simple, entire, and needle-like, up to 3 mm. Flowers are small, bisexual and arranged in cymes. The calyx consists of five distinct sepals. The corolla has five bright yellow petals shaped like the blades of a propeller. Anthers are numerous. The gynoecium has 3 (sometimes 4) locules, and the ovary is superior. Ovules are numerous (ca 22,) and with parietal placentation. The style has 3 (sometimes 4) white lobes. Fruits are small capsules, red when immature and dark purple at the time of dehiscence. Mature seeds are small and dark brown. Fire kills aboveground individuals, but seeds in the soil survive fire and form long-lived seed banks. Fire suppression and alteration of fire regimes constitute a threat for this species because of its dependence on fire to release local populations from competitive exclusion.

Phenology: Reproduction takes place between April and October, but most flowering and fruiting takes place between June and September. Stems senesce at the end of the reproductive season and new ones sprout for the base in late winter-early spring. Flowering branches are many-flowered and indeterminate. Flowers develop acropetally and are exposed one at a time or in small numbers (up to 8 per branch). New flowers open early in the morning and the petals curl up by noon. It takes approximately 25 days between fertilization and fruit dehiscence. The mature capsules remain attached to the stem after realizing the seeds. Seeds do not show any obvious primary dispersal mechanism and probably are dispersed by gravity. Most germination of H. cumulicola occurs during winter and early spring, but many seedling do not emerge from the sand until April-May. Seedling recruitment is highly variable between years.

Breeding System and Pollination: H. cumulicola is self-compatible, but requires the services of pollinators to set seed. Native solitary bees (Dialictus spp. and Augochloropsis spp.) appear to be the primary pollinators. Other visitors include Geron sp. Copestilium nigrum and Bombus sp. Pollinator visitation occurs at similar rates regardless of flower or plant density.

Genetics: H. cumulicola populations have a high degree of genetic differentiation among populations (F_st = 0.72, n = 34) and low expected heterozygosity. At population level, there is spatial patterning of multi-locus genotypes among gaps. Across all gaps, genetic similarity is higher than expected for plants growing within about 10 m of each other, and is highest within 3 m. Plants more distant than about 10 m are not particularly similar to each other genetically. However, there is no genetic spatial pattern within individual gaps.

Population Dynamics: A population viability analysis (based on matrix modeling) indicated that long-term persistence of H. cumulicola in Florida rosemary scrub requires fire. Fire intervals shorter than 50 years may imperil local persistence of most populations, and longer intervals without fire may eliminate even the largest populations. High risks of population extinction without frequent fires, limited seed dispersal ability, high population differentiation, greater occurrence in large and aggregated patches, and similar demographic responses in occupied and non-occupied Florida rosemary scrub patches indicate the possibility for regional metapopulation dynamics in H. cumulicola.

Interesting Facts: This species, as other Hypericum, may contain hypericin, a promising compound providing protective control of viral diseases (Duke 1989) and anti-depressant action (Ullman 1997).

 Data Collected by Archbold Biological Station’s Plant Ecology Lab: We have collected annual census data (4993 individuals, 1994-2002) from 15 sites across a gradient of time-since-fire in Archbold Biological Station. We have also collected annual census data from natural and human-modified habitats in the Lake Wales Ridge Forest   (2320 individuals, 1996-2001). Monthly, quarterly and biannual data was obtained during several germination and seedling survival experiments and observation trials. We have estimated seed production (1994-2001). We counted the number of flowers, fruits, and reproductive buds for each studied individual during their reproductive peak in August-September of each year, except 1997 and 1999. We used linear regressions relating plant height and number of reproductive structures (logarithm transformed data) to estimate number of fruits in these 2 years (all r2 > 0.75, n = 20 per site). In 1995, 1996, and 1998 the most distal mature fruit of randomly selected individuals in each population was also collected, and number of viable seeds counted. Allozyme analysis allowed the resolution of 18 loci, with 6.2 mean percent loci polymorphic .

Data Availability: [Appendix 1., Conservation Biology 17:433-449, 2003 We have available 70 projection matrices used as the basis for the population viability analysis model. We defined six life-history stages: (1) seeds in the seed bank; (2) a single stage of first-year plants (seedlings) at census time; (3) a single vegetative stage, and three reproductive classes (4) small flowering individuals, 12-33 cm tall; (5) medium flowering individuals, 34-50 cm; and (6) large flowering individuals, >50 cm.

Contact Person: Pedro F. Quintana-Ascencio

References:

1. Coile, N. C. 2000. Notes on Florida’s endangered and threatened plants. Report. Florida Department of Agricultural and Consumer Services, Division of Plant Industry, Gainesville.
2. Christman, S. P., and W. S. Judd. 1990. Notes on plants endemic to Florida scrub. Florida Scientist 53: 52-73.
3. Dolan, R. W., R. Yahr, E. S. Menges, and M. D. Halfhill. 1999. Conservation implications of genetic variation in three rare species endemic to Florida rosemary scrub. American Journal of Botany 86: 1556-1562.
4. Menges, E. S., R. W. Dolan, R. Yahr, and D. R. Gordon. 2001. Comparative genetics of seven plant endemic to Florida’s Lake Wales Ridge. Castanea 66: 98-114.
5. Menges, E. S., R. W. Dolan, D. R. Gordon, M. E. K. Evans, and R. Yahr. 1998. Demography, ecology and preserve design for endemic plants of the Lake Wales Ridge, Florida. Final report. Nature Conservancy’s Ecosystem Research Program, Archbold Biological Station, Lake Placid, Florida.
6. Boyle, O. D. and E. S. Menges. 2001. Pollinator visitation to Hypericum cumulicola (Hypericaceae), a rare Florida scrub endemic. Florida Scientist. 64: 107-117.
7. Quintana-Ascencio, P. F., and E. S. Menges. 1996. Inferring metapopulation dynamics from patch-level incidence of Florida scrub plants. Conservation Biology 10: 1210-1219.
8. Quintana-Ascencio, P. F., and E. S.Menges. 2000. Competitive abilities of three narrowly endemic plant species in experimental neighborhoods along a fire gradient. American Journal of Botany 87: 690-699.
9. Quintana-Ascencio, P. F. and M. Morales-Hernández. 1997. Fire-mediated effects of shrubs, lichens and herbs on the demography of Hypericum cumulicola in patchy Florida scrub. Oecologia 112: 263-271.
10. Quintana-Ascencio, P. F., R. W. Dolan, and E. S. Menges. 1998. Hypericum cumulicola demography in unoccupied and occupied Florida scrub patches with different time-since-fire. Journal of Ecology 86: 640-651.
11. Quintana-Ascencio, P. F., E. S. Menges, and C. W. Weekley. 2003. A fire-explicit population viability analysis of Hypericum cumulicola in Florida rosemary scrub. Conservation Biology, 17:433-449. [Appendix 1. Projection matrices.]

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