Prunus geniculata
Encyclopedia
Prunus geniculata is a rare species of plum
known by the common name scrub plum. It is endemic to Florida
in the United States, where it occurs on the Lake Wales Ridge
in the central ridges of the peninsula. It is threatened by the loss of its habitat and is a federally listed endangered species
of the United States.
This plant is a low, rounded shrub
with a gnarled trunk emerging from the sand and branching densely to form a mound up to two meters tall. The zig-zagging, angled, sharp-tipped branches are sometimes buried in sand and emerge covered in lichen
s. The gray bark
cracks, revealing new reddish brown bark beneath. The alternately arranged leaves have smooth blades 1 to 3 centimeters long with wavy or toothed edges. Blooming occurs before the leaves appear. The flowers are usually solitary. They have five red sepal
s and five white petals a few millimeters long. There are many stamen
s at the center, each with a yellow anther. The species is andromonoecious
, with individuals bearing both bisexual and male-only flowers. The fruit is a bitter-tasting, egg-shaped drupe
up to 2.5 centimeters long. The drupe is reddish purple in color and is consumed by animals.
This plant grows in yellow-sand sandhill
habitat dominated by longleaf pine and turkey oak and white-sand Florida scrub
among sand pine, Florida rosemary
, and scrub hickory. The plant may be solitary or it may grow colonially. Little is known about the plant's life history
.
The plant's native habitat is maintained by periodic wildfire
. The natural fire regime
in the area produces openings in the vegetation, removing woody, overgrown plants in the canopy and creating gaps where the smaller plants can receive sun. This shrub cannot tolerate shade and it thrives when fire clears the vegetation around it. It resprouts from its fibrous root system after its aboveground part burns. Flowering increases in the seasons after a fire, then decreases the longer the area goes unburned. The plant is long-lived, has low mortality, and can survive many years without fire. However, fire suppression is the major threat to the survival of the species.
Another threat to the species is the outright loss of its habitat in the conversion to residential and agricultural properties, including citrus
groves. The plant's own biology may contribute to its rarity: germination
rates are low and many of the developing fruits are lost before they mature, either to abortion or predation. The species then experiences low recruitment
, with few seedlings joining the population.
As of 2008 there were 83 populations counted, but 39 of these contained fewer than 10 plants each. Most populations are on the Lake Wales Ridge, and a few are on adjacent ridges. Half the populations are on private land, but most of the large populations are in protected or managed
areas.
Plum
A plum or gage is a stone fruit tree in the genus Prunus, subgenus Prunus. The subgenus is distinguished from other subgenera in the shoots having a terminal bud and solitary side buds , the flowers in groups of one to five together on short stems, and the fruit having a groove running down one...
known by the common name scrub plum. It is endemic to Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
in the United States, where it occurs on the Lake Wales Ridge
Lake Wales Ridge
The Lake Wales Ridge is a low ridge running for about 150 miles south to north in Central Florida. The greater part of the ridge is in Highlands County and Polk County, but it extends north into Osceola, Orange and Lake Counties. It is named for the city of Lake Wales, roughly at the mid point of...
in the central ridges of the peninsula. It is threatened by the loss of its habitat and is a federally listed endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
of the United States.
This plant is a low, rounded shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
with a gnarled trunk emerging from the sand and branching densely to form a mound up to two meters tall. The zig-zagging, angled, sharp-tipped branches are sometimes buried in sand and emerge covered in lichen
Lichen
Lichens are composite organisms consisting of a symbiotic organism composed of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...
s. The gray bark
Bark
Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...
cracks, revealing new reddish brown bark beneath. The alternately arranged leaves have smooth blades 1 to 3 centimeters long with wavy or toothed edges. Blooming occurs before the leaves appear. The flowers are usually solitary. They have five red sepal
Sepal
A sepal is a part of the flower of angiosperms . Collectively the sepals form the calyx, which is the outermost whorl of parts that form a flower. Usually green, sepals have the typical function of protecting the petals when the flower is in bud...
s and five white petals a few millimeters long. There are many stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...
s at the center, each with a yellow anther. The species is andromonoecious
Plant sexuality
Plant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....
, with individuals bearing both bisexual and male-only flowers. The fruit is a bitter-tasting, egg-shaped drupe
Drupe
In botany, a drupe is a fruit in which an outer fleshy part surrounds a shell of hardened endocarp with a seed inside. These fruits develop from a single carpel, and mostly from flowers with superior ovaries...
up to 2.5 centimeters long. The drupe is reddish purple in color and is consumed by animals.
This plant grows in yellow-sand sandhill
Sandhill
A sandhill is a type of ecological community or xeric wildfire-maintained ecosystem. It is not the same as a sand dune. It features very short fire return intervals, one to five years. Without fire, sandhills undergo ecological succession and become more oak dominated.Entisols are the typical...
habitat dominated by longleaf pine and turkey oak and white-sand Florida scrub
Florida scrub
Florida scrub is an endangered temperate coniferous forest ecoregion of the state of Florida in the United States. It is found on coastal and inland sand ridges and is characterized by a xeromorphic plant community dominated by shrubs and dwarf oaks. Scrub soils, a type of entisol, are derived...
among sand pine, Florida rosemary
Ceratiola ericoides
The Sandhill-rosemary, Florida-rosemary or Sand heath, Ceratiola ericoides, is a shrub usually included in the plant family Ericaceae, though treated by some botanists in the Empetraceae....
, and scrub hickory. The plant may be solitary or it may grow colonially. Little is known about the plant's life history
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
.
The plant's native habitat is maintained by periodic wildfire
Wildfire
A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...
. The natural fire regime
Fire regime
A fire regime is the pattern, frequency and intensity of the bushfires and wildfires that prevails in an area. It is an integral part of fire ecology, and renewal for certain types of ecosystems. If fires are too frequent, plants may be killed before they have matured, or before they have set...
in the area produces openings in the vegetation, removing woody, overgrown plants in the canopy and creating gaps where the smaller plants can receive sun. This shrub cannot tolerate shade and it thrives when fire clears the vegetation around it. It resprouts from its fibrous root system after its aboveground part burns. Flowering increases in the seasons after a fire, then decreases the longer the area goes unburned. The plant is long-lived, has low mortality, and can survive many years without fire. However, fire suppression is the major threat to the survival of the species.
Another threat to the species is the outright loss of its habitat in the conversion to residential and agricultural properties, including citrus
Citrus
Citrus is a common term and genus of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar and the Yunnan province of China...
groves. The plant's own biology may contribute to its rarity: germination
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...
rates are low and many of the developing fruits are lost before they mature, either to abortion or predation. The species then experiences low recruitment
Recruitment (biology)
In biology, recruitment occurs when juvenile organisms survive to be added to a population. The term is generally used to refer to a stage whereby the organisms are settled and able to be detected by an observer....
, with few seedlings joining the population.
As of 2008 there were 83 populations counted, but 39 of these contained fewer than 10 plants each. Most populations are on the Lake Wales Ridge, and a few are on adjacent ridges. Half the populations are on private land, but most of the large populations are in protected or managed
Land management
Land management is the process of managing the use and development of land resources. Land resources are used for a variety of purposes which may include organic agriculture, reforestation, water resource management and eco-tourism projects.-See also:*Sustainable land management*Acreage...
areas.