CPC Plant Profile: Crenulate Leadplant
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Plant Profile

Crenulate Leadplant (Amorpha herbacea var. crenulata)

This picture shows a single flower spike amongst small, dark green leaflets on reddish branches. Photo Credit: Jennifer Possley
Description
  • Global Rank: T1 - Critically Imperiled
  • Legal Status: Federally Endangered
  • Family: Fabaceae
  • State: FL
  • Nature Serve ID: 136484
  • Date Inducted in National Collection: 01/01/1985

Amorpha crenulata, a semi-deciduous shrub, blooms with several flower spikes in the spring that range in color from white and orange to blue and purple. Numerous small, dark green leaflets grow on its reddish branches. The species' subpopulations is threatened by deforestation and fragmentation in order to accommodate Florida's growing population which accounts for 99% of loss, as well as heavy fire suppression and excessive drainage of its habitats' water supply. It is also pitted against invasive plant species such as Brazilian peppertrees, cane grass, purple orchid trees, and various grape vine species.

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Updates
Jennifer Possley
  • 01/06/2022

Crenulate lead plant (Amorpha herbacea var. crenulata)

When CPC announced the new, network-wide seed ageing research project launched in partnership with IMLS and NLGRP, the crenulate lead plant (Amorpha herbacea var. crenulata) seemed like a natural fit for Fairchild Tropical Botanic Garden. This federally endangered, fire-dependent Miami endemic sub-shrub was one of the species that Fairchild’s conservation team has worked with from the beginning (i.e., the 1980s).  Unfortunately, since that time, crenulate lead plant populations have significantly diminished. The largest population was developed into a car wash and the remaining populations are on protected land, but are severely fire-suppressed.

Due to the long-term fire-suppression, the remaining wild crenulate lead plants rarely flower and fruit.  Yet we have observed plants respond to vigorous pruning with abundant blooms.  Fairchild conservation horticulturist thus suggested we give the wild plants a heavy pruning in the spring to mimic a fire.  With help from Miami-Dade Natural Areas Management, we visited one population in a Miami-Dade Environmentally Endangered Lands Preserve and we hacked away!  Within a month, plants were vigorously flowering.  We later put organza bags over developing seeds and waited until late summer, when we were able to harvest thousands of seeds.  We were easily able to contribute 800 seeds for NLGRP’s advance ageing study, and we can’t wait to see the results of this exciting research!

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Center for Plant Conservation
  • 11/25/2021
  • Reintroduction

Although historically known from 1916 collections at Site 25, by the 1990s Amorpha herbacea var. crenulata was missing from the park. In the wake of Hurricane Andrew in 1992, there was much concern about optimal microsites for supporting this federally endangered species. In 1995, into the park’s pine rockland Fairchild Tropical Botanical Garden reintroduced 190 plants with stages ranging from seedling to adult into 7 plots along a gradient and measured elevation and distance from the bay for each. We monitored plants in 1996, 200 and 2008. By 2008, although survival depended upon plot, there was no relationship between elevation or distance from bay and whole plant survival or recruitment of new seedlings. By 2008, 69 (36%) of original transplants survived and 3725 new seedlings recruited. By 2008, overall survival of stage seedling, juvenile and adult plants was 63%, 36%, and 34%, respectively.

Center for Plant Conservation
  • 10/27/2021
  • Reintroduction

Fairchild expanded its test of whether translocation outside the known historic range of the endangered crenulate leadplant (Amorpha herbacea var. crenulata) could be a viable conservation alternative. In August 2007, we introduced 245 plants into four microhabitats along a pine rockland/transverse glade gradient with similar attributes to historically known and current South Florida occurrences. After one year survival of transplants was best in pineland habitat (92%), while survival in ecotone(73%), grassy glade (75%), and restored glade(66%)was significantly less. As was true in our pilot study, Amorpha does not grow well with heavy competition especially with grasses. Their superior survival in pineland habitats is probably related to lack of competition and slightly higher soil moisture in this habitat.

Center for Plant Conservation
  • 10/27/2021
  • Reintroduction

Although regulatory agencies caution against translocation outside of known historic ranges, when most wild populations and their habitats have been altered or destroyed few viable options may be available for conserving rare plants. To test whether translocation outside its known historic range could be a viable conservation alternative for the endangered crenulate leadplant (Amorpha herbacea var. crenulata) we introduced it into four microhabitats along a pine rockland/transverse glade gradient with similar attributes to historically known and current South Florida occurrences. Survival of transplants was 100% in all microhabitats after one year, but plant growth was highest in the restored glade and ecotone. After 2 years, survival was 80% in all but grassy glade habitat, which had 52% survival. Plants with higher net CO2 assimilation growing on soils with higher pH, less grass cover, and less water content exhibited significantly greater growth. Initial transplants are growing well in the novel habitat outside the historic range, however continued monitoring for new recruits and ongoing site management are essential for long-term success.

Center for Plant Conservation
  • 10/27/2021
  • Reintroduction

Though translocations of rare populations should be considered only as the last resort for species’ conservation, when habitat destruction is imminent, it may be the only means to preserve a species. With over half of the known wild federally endangered Amorpha herbacea var. crenulata (Crenulate lead plant) growing on unprotected land slated for development, preserving this population was critical. We rescued whole plants, cuttings and seeds for an experimental translocation. Into a restored pine rockland, once dominated by Schinus terebinthifolius (Brazilian pepper), we transplanted plants from different sources and of different sizes. Plants used as source stock for the introduction were from an unprotected site, seedlings, and 1-, 2- and 7-year-old plants from Fairchild Tropical Botanic Garden’s ex situ collection. We evaluated which propagule type and source had the best survival, growth and reproduction. After 40 months, overall transplant survival was 71%. Large whole plants, rescued and nursery grown, had the best survival rates (86 and 78%); whereas cuttings had 67% survival and seedlings had only 26% survival. The Restored Site, once nearly a monoculture of S. terebinthifolius, is now dominated by 106 native plant species, including 17 naturally recruited state listed plant species. In addition, one federally threatened snake species was observed on the site. These studies demonstrate that botanic garden collections not only play a vital role in the conservation of species’ genetic diversity, but also can be used as source material for habitat restoration.

Center for Plant Conservation
  • 08/17/2021
  • Orthodox Seed Banking

In 2021, CPC contracted the Fairchild Tropical Botanic Garden to recollect seed from a population currently held in long term orthodox seed storage as part of an IMLS-funded seed longevity experiment. The National Laboratory for Genetic Resources Preservation will evaluate how germination tested viability and RNA Integrity of seed lots decline over time in storage.

  • 10/09/2020
  • Reproductive Research

Pollination, propagation and seed storage at Fairchild Tropical Gardens (Garvue 1988).

  • 10/09/2020
  • Living Collection

Fairchild maintains a small ex situ conservation collection of plants, both in the nursery and planted in the garden. Hundreds of seeds from multiple populations (including extirpated ones) have been banked at NLGRP and at Fairchild. Other local organizations, including some native plant nurseries, also maintain small ex situ collections.

  • 10/09/2020
  • Seed Collection

Fairchild maintains a small ex situ conservation collection of plants, both in the nursery and planted in the garden. Hundreds of seeds from multiple populations (including extirpated ones) have been banked at NLGRP and at Fairchild. Other local organizations, including some native plant nurseries, also maintain small ex situ collections.

  • 11/05/2017

The most critical action needed for the conservation of Crenulate lead plant is to conduct prescribed burns in the fire-adapted, urban habitats in which it grows.  Fairchild will continue with the important actions of population monitoring and seed banking indefinitely.  

J. Possley
  • 11/05/2017
  • Orthodox Seed Banking

Fairchild maintains a small ex situ conservation collection of plants, both in the nursery and planted in the garden.  Hundreds of seeds from multiple populations (including extirpated ones) have been banked at NLGRP and at Fairchild.  Other local organizations, including some native plant nurseries, also maintain small ex situ collections.  

J. Possley
  • 11/05/2017
  • Reintroduction

There are two wild populations of Crenulate lead plant in Miami-Dade County totaling approximately 500 individuals.  In addition, there are two populations reintroduced to protected areas, totaling approximately 250 individuals.  One of these reintroduced populations has begun to produce recruits.  Several wild populations of Crenulate lead plant were destroyed or died out in the past two decades.  In 2002, the (at the time) largest population of several hundred plants was destroyed when it was sold to a developer, however many of these plants were rescued for ex situ collection or reintroductions.  Shortly thereafter, a population of <5 plants was lost due to fire suppression and invasive species encroachment, and a similar-sized population was again lost in 2015.  

Nature Serve Biotics
  • 05/02/2017

There are 4 known populations of the taxon, all in Dade County, Florida. Its habitat is restricted and minimal due to encroaching residential and commercial development, fire suppression, and invasion by exotic plants.

Meghan Fellows
  • 01/01/2010

Amorpha herbacea var. crenulata is threatened by habitat destruction, invasive species (Schinus terebinthifolius, Neyraudia reynaudiana, Bauhina variegata, Vitis sp.), fire suppression and mowing (Garvue 1988).

Meghan Fellows
  • 01/01/2010
  • Propagation Research

Current research summary includes investigating relationships with Mycorrhizae (Fisher 2000). Pollination, propagation and seed storage at Fairchild Tropical Gardens (Garvue 1988).

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Photos
Nomenclature
Taxon Amorpha herbacea var. crenulata
Authority Isely
Family Fabaceae
CPC Number 107
ITIS 182063
USDA AMHEC
Common Names Crenulate Lead-Plant | Clusterspike False Indigo
Associated Scientific Names Amorpha herbacea var. crenulata | Amorpha crenulata
Distribution This shrub is known from the Miami Rock Ridge Pinelands, an extremely rare and threatened ecosystem which contains over 40 endemic species. Historically, it was found in the pinelands of Dade County, but now occurs in the south Miami/Kendall area.
State Rank
State State Rank
Florida S1
Habitat

This lead plant can be found in several habitats: in pine rocklands, pinelands hammock edges, vacant lots, marl prairie, and fire-maintained areas. Historically, this species has also been seen in the edges of wet prairies as well as communities associated with seasonally hydrated soils and frequent burning. This species can tolerate varying light conditions, soil depth, and litter depth.

Ecological Relationships

Ecological associations include the following species: Florida slash pines, saw palmettos, cabbage palmettos, southern sumacs, Florida little bluestems, Carolina wild petunias, gulfdune paspalum, poisonwood, wax myrtles, and bupleurums. Pollinators include western honey bees, the metallic green Agapostemon splendens bee species, and Dianthieium curvatum floridiense, a native leaf-cutting bee found in Florida. Mycorrhizal dependence has been demonstrated.

Pollinators
Common Name Name in Text Association Type Source InteractionID
Bees
Honey bees Apis mellifera Floral Visitor Link
Sweat bees Agapostemon splendens Floral Visitor Link
Leaf-cutting bees Dianthidium floridiense Floral Visitor Link
Flies
Diptera Floral Visitor Link
Reintroduction
Lead Institution State Reintroduction Type Year of First Outplanting
Fairchild Tropical Botanical Garden Florida Reintroduction 1995
Fairchild Tropical Botanical Garden Florida Assisted Colonization 2002
Fairchild Tropical Botanical Garden Florida Reintroduction 2006

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