Dicerandra frutescens
| Dicerandra frutescens | |
|---|---|
| |
| Scientific classification | |
| Kingdom: | Plantae |
| Division: | Magnoliophyta - Flowering plants |
| Class: | Magnoliopsida - Dicotyledons |
| Order: | Lamiales |
| Family: | Lamiaceae ⁄ Labiatae |
| Genus: | Dicerandra |
| Species: | D. frutescens |
| Binomial name | |
| Dicerandra frutescens Shinners | |
| |
| Natural range of Dicerandra frutescens from USDA NRCS Plants Database. | |
Common name: scrub balm
Contents
Taxonomic notes
Description
D. frutescens is a short-lived perennial, suffruticose species with a shallow tap root (Huck 1987; Menges 1992). There are two types of shoots: vegetative and reproductive[1]. Species of Dicerandra contain essential oils and terpenoid mixtures that gives each species an unique odor (McCormick et al. 1993).
It can be distinguished from D. christmanii, another scrub mint found narrowly distributed along the Lake Wales Ridge, by having a minty aroma, longer leaves, and deep purple anthers (Huck et al. 1989).
Distribution
Distribution is limited to the excessively yellow drained sand of the southern portion of the Lake Wales Ridge (Menges 1992).
Ecology
Habitat
D. frutescens can be found to occupy a small range in the southern portion of the Lake Wales ridge in xerophytic scrub oak communities on excessively drained yellow sands (FSU Herbarium; Menges 1999). Specific sand types include Astatula and Paola and Orsino (Menges 1992). It often can be seen growing in gaps due to the high soil water availability, light levels, and low leaf litter accumulation (Weedley et al. 2007). Populations have been observed in disked areas such as fire lanes (Menges 2008). Associated species include Lyonia ferruginea, Persea humilis, Carya floridana and Quercus laevis (Menges 1992).
Phenology
The flowers of D. frutescens are perfect and reproduce with outcrossing and are self compatible (Evans et al. 2003). The upper lip of the flower is marked internally with a purple trellis pattern of lines and dots, the lower lip is maculate with larger spots from lobe bases to the base of the lip [1]. It has two pairs of stamen, with one pair being slightly longer and spurred anthers for insect pollination (Kral 1983). Flowers occur August through winter and fruit September through winter.
Seed dispersal
Seed bank and germination
In a pyrogenic habitat such as the scrub habitat, it is expected that endemic species show positive germination responses to smoke exposure. Populations of D. frutescens have been observed to flourish shortly after fire; however, smoke has been observed to not stimulate seed germination. This phenomenon could be due to germination from a persistent soil seed bank (Lindon et al. 2008). Scrub fires have a tendency to be patchy and reproductive individuals might not come in contact with the fire, these survivors may be the reason populations flourish shortly after fire (Menges 1992).
Fire ecology
The xerophytic scrubs of the Lake Wales Ridge rely on fire to maintain species composition and health. Optimum fire interval for reducing extinction risk for D. frutescens is 6 to 12 years (Menges 2006). With fire suppression, there is a negative effect of the fecundity and recruitment of medium and large flowering plants; however, there is a positive effect on seedling survival (Evans et al. 2010). D. frutescens are often found in open gaps, with an increase in time since fire, there is a decrease in the amount of gaps found in the scrub habitat. This causes a decrease in soil moisture availability and sunlight, along with an accumulation of litter, which can prove unfavorable to D. frutescens (Evans et al. 2010). Increasing the time since fire also suppresses flowering, either by increasing the chances of the individual changing from a reproductive state to the vegetative state, or by decreasing the chances an individuals will change from the vegetative state to a reproductive state (Evans et al. 2008).
Scrub fires have a tendency to be patchy, causing some individuals to be unaffected by fire, these survivors may be important in recolonizing site by seed dispersal (Menges 1992).
Pollination
It has spurred anthers that require triggering by insects to release and disperse the pollen [1]. It is mainly pollinated by bee-flies (Exoprosopa fasciata) (Evans et al. 2003). Pollinators have been observed to visit flowers in the sun more than three times higher than flowers occurring in the shade (Deyrup and Menges 1997). Reproduction has been shown to have a positive correlation with population size and density (Evans et al. 2003).
The following Hymenoptera families and species were observed visiting flowers of Dicerandra frutescens at Archbold Biological Station (Deyrup 2015):
Apidae: Apis mellifera, Bombus impatiens, B. pennsylvanicus
Halictidae: Augochlorella aurata, Lasioglossum placidensis
Megachilidae: Megachile petulans
Use by animals
Diseases and parasites
Conservation and Management
Cultivation and restoration
Photo Gallery
References and notes
Deyrup, M.A. and N.D. 2015. Database of observations of Hymenoptera visitations to flowers of plants on Archbold Biological Station, Florida, USA.
Florida State University Robert K. Godfrey Herbarium database. URL: http://herbarium.bio.fsu.edu. Last accessed: October 2015. Collectors: P. Alcorn, Steven P. Christman, Robert K. Godfrey, Walter S. Judd, J.D. Skean. States and Counties: Florida: Highlands. Compiled by Tall Timbers Research Station and Land Conservancy.
