Crotalaria avonensis - K.R. DeLaney & Wunderlin
Avon Park Rabbit-bells
Other English Common Names: Avon Park Harebells, Avon Park Rattlebox
Other Common Names: Avon Park rattlebox
Taxonomic Status: Accepted
Related ITIS Name(s): Crotalaria avonensis K.R. DeLaney & Wunderlin (TSN 501802)
Unique Identifier: ELEMENT_GLOBAL.2.148066
Element Code: PDFAB160Q0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Pea Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Fabales Fabaceae Crotalaria
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Crotalaria avonensis
Conservation Status
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NatureServe Status

Global Status: G1
Global Status Last Reviewed: 29Feb2000
Global Status Last Changed: 20Sep1989
Rounded Global Status: G1 - Critically Imperiled
Reasons: A narrowly distributed central Florida endemic, known from only three sites in Polk and Highlands counties, Florida. The mass development occurring on the Central Florida Ridge threatens this species. The site with the largest population suffers fragmentation due to a housing development.
Nation: United States
National Status: N1

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Florida (S1)

Other Statuses

U.S. Endangered Species Act (USESA): LE: Listed endangered (27Apr1993)
Comments on USESA: Listed endangered by USFWS on April 27, 1995.
U.S. Fish & Wildlife Service Lead Region: R4 - Southeast

NatureServe Global Conservation Status Factors

Range Extent Comments: Crotalaria avonensis is an endemic to the xeric white sand scrub of the Lake Wales ridge of central Florida. Only three populations are known and they are all in Polk and Highlands counties near Avon Park. DeLaney and Wunderlin (1989) suggest that the species is a Miocene relic endemic to the southern Lake Wales Ridge.

Number of Occurrences: 1 - 5
Number of Occurrences Comments: Known from only three sites (Endangered Species Tech. Bull., 1992).

Overall Threat Impact Comments: Habitat threatened by conversion to citrus groves, cattle pastures, or housing subdivisions. The site with the largest known population is laid out as a mostly undeveloped subdivision, but with roads and scattered houses making landscape management of the habitat difficult (L. Morse, pers. obs., Feb. 2000).

Intrinsic Vulnerability Comments: Threatened mainly by habitat loss; often found in open and somewhat disturbed areas such as trail edges, also tolerates partial shade. (see ES file)

Other NatureServe Conservation Status Information

Distribution
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Global Range: Crotalaria avonensis is an endemic to the xeric white sand scrub of the Lake Wales ridge of central Florida. Only three populations are known and they are all in Polk and Highlands counties near Avon Park. DeLaney and Wunderlin (1989) suggest that the species is a Miocene relic endemic to the southern Lake Wales Ridge.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map

U.S. & Canada State/Province Distribution
United States FL

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
FL Highlands (12055), Polk (12105)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
03 Kissimmee (03090101)+, Peace (03100101)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A perennial herb growing from a taproot. Stems grow upright from the taproot for only a few centimeters, then terminate in flower clusters. Leaves are rounded, 1-2 cm long, with white-yellow hairs. Flower petals are yellow.
Technical Description: Perennial, erect, virgate or slightly spreading herbs with a taproot to 14 mm thick, to 40 cm long, sometimes branching into 2-8 stout, semi-radially disposed secondary roots to 7 mm thick, and to 14 cm long. Flowering stems 1-3(10), 2-10(18) cm long, arising from the tap root from up to 10 cm below the surface, moderately sericeous, with ascending, loosely appressed, white or yellowish-white trichomes (0.3) 0.6-1.4 mm long, the longest internodes 8-12 mm long. Stipules absent. Leaves broadly elliptic to orbicular, (5) 8-19 mm long, (4) 7-16 mm wide, apiculate, somewhat succulent, both surfaces with white or yellowish-white, loosely appressed trichomes 0.3-1.2 mm long, the base rounded to broadly cuneate, the apex obtuse to emarginate; petioles reddish-brown or green, relatively stout, 1.5-2.8 mm long. Racemes terminal on primary stem and on short leaf-opposed secondary branches; peduncles (1) 10-17 (33) mm long. Bracts with a petiole of ca. 0.5 mm, linear-elliptic, 1.5-2.4 (4.5) mm long, 0.2-0.3 (0.7) mm wide. Pedicels 2-3 mm long; buds obliquely conical, angular. Calyx 7-8 mm long, the tube 2-2.5 mm long with white trichomes (0.3) 0.6- 1.2 mm long; bracteoles linear -elliptic, 1.6-2.0 (2.6) mm long, 0.4- 0.5 mm wide. Corollas yellow, standard (the large upper petal) variably brownish-red-lineolate, obovate, 8.0-8.7 (10) mm long, 5.3-7.2 mm wide, 1-2.5 mm longer than the upper calyx lobes, the blade rounded at the apex, truncate, sometimes emarginate, each half with a thickened fleshy area near its base, woolly, sometimes ciliate near the base; appendages at the base of the blade triangular, bilobed or absent; the wing petals (the lateral ones) held above and at a slight angle to the keel (the lower boat-shaped pair of petals), 6.8-8.3 (9.0) mm long, 2.5-3.1 (3.5) mm wide, narrowly obovate, transversely rugose on the outer surfaces, usually ciliate at the base below; the keel ca. 4 mm long, smoothly incurved, with a beak ca. 1 mm long, with only a slight twist (less than 90 deg.) at the tip, slightly protruding into the lower median groove of the standard, upper and lower free edges slightly ciliate; anthers of two lengths, the elongate ones, basifixed, ca. 1.2-1.4 mm long, the short ones, medifixed, 0.3-0.5 mm long; ovary 1.6-2.7 mm long, glabrous or with only a few short trichomes along the dorsal suture near the base of the style, 0.8-1.1 mm wide, stipe ca. 1 mm long, style smoothly incurved below the middle, 3-3.5 mm long, barbellate on the distal (sometimes also the basal) adaxial surface and around the stigma. Fruits inflated, tan to gray to maroon, glabrous or with only a few short trichomes along the distal portion of the dorsal suture, 14-25 mm long, 5.9-7.8 mm wide, the stipe 1.5-2.0 mm long; seeds chestnut to maroon, up to 18 per pod, 3.4-3.8 mm long, ca. 2.4-2.6 mm wide. (from DeLaney and Wunderlin 1989 with minor modifications).
Diagnostic Characteristics: Crotalaria avonensis is found only on the white sand scrub and is recognized by its yellow flowers, inflated fruit, and erect (sometimes bushy) habit. It can easily be confused with C. rotundifolia (Walt.) Gmelin but differs in its shorter recurved style which can even be seen in the fruit as a persistent appendage, absence of stipules, pubescent lateral petals, and lighter colored fruit.
Duration: PERENNIAL, DECIDUOUS
Reproduction Comments: Crotalaria avonensis blooms from March to June. It is deciduous and has a deep taproot. These factors probably allow it to survive through the dry winter months and the fires that are common in this type of habitat. It may also have an association with an insect which is often found in conspicuously swollen stem tips (K. DeLaney pers. comm.).
Ecology Comments: Occurs in open and disturbed habitats such as trail edges and a former roadbed; also tolerates partial shade (Klaudisova 1991).
Terrestrial Habitat(s): Forest/Woodland, Sand/dune, Shrubland/chaparral, Urban/edificarian, Woodland - Mixed
Habitat Comments: SUMMARY: Upland habitats (scrub and sandhill), often along trails or open edges. Grows in full sun or partial shade. Commonly found with other local endemics such as Small's jointweed (Polygonella myriophylla). END SUMMARY. (R. Wunderlin pers. comm.) or along an old previously disturbed roadbed (unused since 1989) in the Saddleblanket Lakes Preserve (Klaudisova 1991). It grows in full sun or partial shade provided by characteristic scrub shrubs or sand pine (Klaudisova 1991). The species grows on Archbold and Satellite sands and is commonly found with a number of other local endemics and such as Chionanthus pygmaea, Bonamia grandiflora, Calamintha ashei, Conradina canescens, Liatris ohlingerae, Paronychia chartacea, Hypericum cumulicola, Polygonella basiramia and especially Polygonella myriophylla (DeLaney et al. 1990). See DeLaney and Wunderlin (1989) p.323, for a complete list of associates.
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: 1. Preservation of the remaining populations of Crotalaria avonensis.

2. Monitor populations.

3. Research the life history and propagation of C. avonensis with and without disturbance.

Restoration Potential: Although this species may be able to colonize historically preserved sites, this is not a given. Areas which have maintained a high number of other scrub endemics appear to be likely potential habitats. Viable seed set and establishment is unknown. Susan Wallace (Bok Tower Gardens, pers. comm.) reports 35-40% seed germination and transplanted (into pots) seedling survival in the greenhouse. Thus, restoration of populations with propagated material may be possible.
Preserve Selection & Design Considerations: Protect all three sites. Since this species appears to prosper in open areas, any land protected must be large enough to allow for a management procedure that will maintain this condition (i.e., fire). Other considerations should be the proximity of heavily developed land to the protected site.
Management Requirements: The absence of a dense overstory and maintenance of an open understory seems to be crucial for this species. Sites may need protection from exotics and soil degradation. Fire may be useful as a tool although it may be difficult in such an open habitat (see Johnson 1982) and with the close proximity of housing in at least one site. Thinning of encroaching species may be necessary if prescribed burning is not feasible.

No data aside from information on natural fire in scrub (see Management information) for Bonamia grandiflora).

Monitoring Programs: One population has had a preliminary assessment done (Klaudisova 1991). Permanent plots along a transect following an old roadbed have been established, and individual plants labeled.
Management Research Needs: Demographic research, including seed viability and seedling establishment in the field would allow the development of a life table for the species. Research on the effect of disturbance (type, amount, and frequency) on site colonization and adult plant survival is also necessary. The Sun Ray scrub should be surveyed for this species (DeLaney, pers. comm.).
Population/Occurrence Delineation
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Group Name: Lake Wales Ridge 1 - EOSPECS

Minimum Criteria for an Occurrence: Any naturally occurring population of 1 or more individuals in suitable habitat.
Separation Barriers: Patches of dense vegetation that shade out patches of open sand and prevent seed germination and colonization form barriers between populations; also, agriculture, pine plantations, and development.


Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 1 km
Alternate Separation Procedure: N/A
Separation Justification: Seeds for most of these species are dispersed by gravity, thus 1 km of suitable / unsuitable habitat appears to be sufficient to distinguish populations.


Date: 19Sep2003
Author: Norden, A.H. and L.G. Chafin
Population/Occurrence Viability
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Justification: Use the Generic Guidelines for the Application of Occurrence Ranks (2008).
The Key for Ranking Species Occurrences Using the Generic Approach provides a step-wise process for implementing this method.

Key for Ranking Species Element Occurrences Using the Generic Approach (2008).
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 18Jun1991
NatureServe Conservation Status Factors Author: Gerald Guala, FLFO (1991), rev. L. Morse (2000)
Management Information Edition Date: 18Jun1991
Management Information Edition Author: Gerald Guala, FLFO
Element Ecology & Life History Edition Date: 18Jun1991
Element Ecology & Life History Author(s): Gerald Guala, FLFO

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
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  • Abrahamson, W.G. 1984b. Species response to fire on the Florida Lake Wales Ridge. American J. Botany 71(1): 35-43.

  • Author unknown. March-June 1991. Report for The Nature Conservancy on the monitoring of Polygala lewtonii, Nolina brittoniana, Prunus geniculata, Crotalaria avonensis and Bonamia grandiflora in the Lake Wales Ridge area Polk County, Florida.

  • Delaney, K., R. Wunderlin, and B. Hansen. 1990. Status report on Crotalaria avonensis. Unpublished report for the U. S. Fish and Wildlife Service.

  • Delaney, K.R., and R.P. Wunderlin. 1989. A new species of Crotalaria (Fabaceae) from the Florida Central Ridge. Sida 13(3): 315-324.

  • Johnson, A.F. 1982. Some demographic characteristics of the Florida rosemary, Ceratiola ericoides. American Midland Naturalist 108:170-174.

  • KRAL, R. 1983.A REPORT ON SOME RARE,THREATENED,OR ENDANGEREDFOREST-RELATED VASCULAR PLANTS OF THE SOUTH.VOL I ISOETACEAETHROUGH EUPHORBIACEAE;VOL II AQUIFOLIACEA THROUGH ASTERACEAE& GLOSSARY.USDA FOREST SERV,SE REG.,ATL,GA. TECH PUBL R8-TP2

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Klaudisova, A. 1991. Report for The Nature Conservancy on the monitoring of Polygala lewtonii, Nolina brittoniana, Prunus geniculata, Crotalaria avonensis, and Bonamia grandiflora in the Lake Wales Ridge area, Polk County, Florida. March-June 1991.

  • Kral, R. 1983c. A report on some rare, threatened, or endangered forest-related vascular plants of the South. U.S. Dept. of Agriculture Forest Service Technical Publication R8-TP2, Athens, GA. 1305 pp.

  • U.S. Fish and Wildlife Service. 1993. Endangered or threatened status for seven central Florida plants. Federal Register 58(79): 25746-25755.

  • WUNDERLIN, RICHARD P. 1982. GUIDE TO THE VASCULAR PLANTS OF CENTRAL FLORIDA. UNIV. PRESSES OF FLA., TAMPA, ST. PETERSBURG, FT. MEYERS, SARASOTA

  • Wunderlin, R.P. 1982. Guide to the vascular plants of central Florida. Univ. Presses Florida, Gainesville. 472 pp.

  • Wunderlin, R.P. Guide to the vascular plants of Florida. University Press of Florida. Gainesville, FL 32611.

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