CPC Plant Profile: Lakela's Mint
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Plant Profile

Lakela's Mint (Dicerandra immaculata)

Dicerandra immaculata produces flowers primarily from September through November. Flowers are formed in whorls of 1-3 flowers per leaf axil. Photo Credit: Steve Shirah © 1991
Description
  • Global Rank: G1 - Critically Imperiled
  • Legal Status: Federally Endangered
  • Family: Lamiaceae
  • State: FL
  • Nature Serve ID: 159688
  • Date Inducted in National Collection: 04/04/1991

Lakela's mint is a small, fragrant, perennial shrub that was listed in 1985 as federally threatened. It faces a high risk of extinction because so much of its habitat has been lost and its populations are so fragmented. This species is known from only one wild population (USFWS 1999). Dicerandra immaculata can be differentiated from others in the Dicerandra genus by its lavender-rose colored flower that has no spots on it. As it grows, it forms small mats or domes of ascending to spreading or sprawling branches. The main leaves are horizontal or pointing upwards, while those with flower clusters sometimes point downward that appear in September through November (USFWS 1999). Its anthers have tiny spurs, while its stamens extend beyond the flower. Both the stems and leaves have a strong mint odor that is unique to the species (Bok Tower Gardens, unpublished data).

Participating Institutions
Updates
Center for Plant Conservation
  • 08/18/2021
  • Orthodox Seed Banking

In 2021, CPC contracted the Bok Tower Gardens 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.?

  • 10/17/2020
  • Cryo

Living plants are important to maintain in an ex situ collection to provide source material of cuttings for introduction and augmentation efforts. Seeds do not retain viability in storage for more than two years, except in -20C or cryogenic temperatures.

  • 10/17/2020
  • Reintroduction

Currently, Lakela's mint is known from a single meta population that is scattered across five of its historical sites. Bok Tower Gardens has introduced three additional populations on protected land This species also occurs at two sites in Hobe Sound National Wildlife Refuge, where it was introduced in 1991 and 1992. (USFWS 1999)

  • 10/17/2020
  • Climate Research

Lakela's Mint is a gap specialist (Richardson et al. 2013). The non-native honey bee is by far the most frequent pollinator, but may negatively impact population dynamics because of its foraging behavior compared to native bees (Richardson et al. 2015). Models of climate change impacts suggest a dramatic decrease in plant number and that increased population size and improved habitat will be vital to prevent extinction (Peterson 2016). Lakela's Mint has an essential oil profile that is unique to it. and the species is tetraploid (Richardson and Peterson 2017).

  • 10/17/2020
  • Demographic Research

Lakela's Mint is a gap specialist (Richardson et al. 2013). The non-native honey bee is by far the most frequent pollinator, but may negatively impact population dynamics because of its foraging behavior compared to native bees (Richardson et al. 2015). Models of climate change impacts suggest a dramatic decrease in plant number and that increased population size and improved habitat will be vital to prevent extinction (Peterson 2016). Lakela's Mint has an essential oil profile that is unique to it. and the species is tetraploid (Richardson and Peterson 2017).

  • 10/17/2020
  • Reproductive Research

A study conducted by researchers at Bok Tower Gardens revealed that Lakela's Mint is a facultative outcrosser: producing higher seed set when it is pollinated by insects than when it reproduces asexually. This study also found that honey bees (Apis mellifera), a non native pollinator, are the most frequent visitor of Lakela mint flowers. Honey bees visit nearly all plants regardless of size. In contrast, native pollinators such as Bombus impatiens prefers to visit flowers on shorter plants (Richardson et al. 2016).

Katie Heineman
  • 09/25/2017

A study conducted by researchers at Bok Tower Gardens revealed that Lakela's Mint is a facultative outcrosser: producing higher seed set when it is pollinated by insects than when it reproduces asexually. This study also found that honey bees (Apis mellifera), a non native pollinator, are the most frequent visitor of Lakela mint flowers. Honey bees visit nearly all plants regardless of size. In contrast, native pollinators such as Bombus impatiens prefers to visit flowers on shorter plants (Richardson et al. 2016).

Nature Serve Biotics
  • 05/02/2017

A narrow endemic, known only from St. Lucie and Indian River counties, Florida. The Florida Natural Areas Inventory's database contains 4 occurrence records. Suitable habitat is rapidly being lost to development.

C.L. Peterson
  • 01/01/2010

Commercial and residential development. Lack of sufficient land management. Reduced native pollinators. Fungal disease. Hybridization with other mints is a serious issue when propagation and collection is not regulated.

C.L. Peterson
  • 01/01/2010

Currently, Lakela's mint is known from a single meta population that is scattered across five of its historical sites. Bok Tower Gardens has introduced three additional populations on protected land This species also occurs at two sites in Hobe Sound National Wildlife Refuge, where it was introduced in 1991 and 1992. (USFWS 1999)

C.L. Peterson
  • 01/01/2010

Lakela's Mint is a gap specialist (Richardson et al. 2013). The non-native honey bee is by far the most frequent pollinator, but may negatively impact population dynamics because of its foraging behavior compared to native bees (Richardson et al. 2015). Models of climate change impacts suggest a dramatic decrease in plant number and that increased population size and improved habitat will be vital to prevent extinction (Peterson 2016). Lakela's Mint has an essential oil profile that is unique to it. and the species is tetraploid (Richardson and Peterson 2017).

C.L. Peterson
  • 01/01/2010

St. Lucie County and Indian River County work to manage Scrub habitat for Lakela's Mint through mechanical treatment and volunteer work days to remove overgrowth and exotics. Fire is recommended but hard to perform in the urban settings (Peterson 2017)

C.L. Peterson
  • 01/01/2010

Purchase and protect privately owned sites. Control off-road-vehicle traffic. Manage habitat. Keep species out of the nursery trade to prevent hybridization. Encourage native pollinators. Use occasional fire to open up habitat. (FNAI 2000)

Philip Gonsiska
  • 01/01/2010

Living plants are important to maintain in an ex situ collection to provide source material of cuttings for introduction and augmentation efforts. Seeds do not retain viability in storage for more than two years, except in -20C or cryogenic temperatures.

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Nomenclature
Taxon Dicerandra immaculata
Authority Lakela
Family Lamiaceae
CPC Number 1404
ITIS 196111
USDA DIIM
Common Names Lakela's Mint | Olga's Mint | Spotless Balm | Spotless-petaled balm
Associated Scientific Names Dicerandra immaculata var. immaculata | Dicerandra immaculata | Dicerandra frutescens var. immaculata
Distribution The range of D. immaculata is very small, being confined to a area one-half mile wide by three miles long in southern Indian River and northern St. Lucie Counties.  It persists in five of its historical sites that are part of one metapopulation.  An experimental population was introduced into Hobe Sound National Wildlife Refuge in Martin County in 1991 and 1992 (Race 1994), and a new population was introduced in St. Lucie County from 2002-2009 by Bok Tower Gardens.
State Rank
State State Rank
Florida S1
Habitat

This endangered taxon is restricted to sand scrub habitats found along the Atlantic Coastal Ridge in ancient dunes formed along former ocean shorelines in Indian River and St. Lucie Counties. These soils consist of highly drained, infertile sands (USFWS 1991). Dicerandra immaculata has been observed growing in both yellow and white sands, and does best in light shade or clearings in the scrub.  It is a gap specialist, and requires open canopy and sand gaps for persistence and recruitment (Richardson et al. 2013). These bare areas were historically maintained by wind action and fires (USFWS 1999).  Other species found in this coastal scrub include sand pine, sand live, myrtle and live oaks, scrub hickory, cabbage palm, hog plum, and tough Bumelia along with some epiphytic species (USFWS 1991).

Ecological Relationships

Known as a "gap" species, D. immaculata thrives in open sunlight and becomes weak when shaded by other plant species (USFWS 1999). It is protected from insect herbivory by the essential oils found in its tissue (McCormick et al. 1993). Lakela's mint is, however, adversely affected by mildew. Mildew grows on the nectary glands, potentially causing destruction of fruits and seeds before they are able to be dispersed (USFWS 1999).  Seed predators are also known to reduce the number of viable seeds.  This species reproduces only through seeds, and insects are needed for successful pollination and seed production.  The primary pollinator is the non-native honey bee, Apis mellifora, which may have negative consequences because it may promote selfing and selectively include plants in sunnier locations, in comparison with native bees (Richardson et al. 2015).  The flowers of this species have spurred anthers, which require insects to trigger them to release and disperse their pollen (USFWS 1987).  Seed dispersal is extremely limited.  Seed from flowering plants in one of the introduced populations was dispersed a maximum of 2 meters away from its maternal plant (Race 1994).

Pollinators
Common Name Name in Text Association Type Source InteractionID
Bees
Honey bees Apis mellifera Confirmed Pollinator Link
Bumble bees Bombus impatiens Confirmed Pollinator Link

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