Microcycas
Encyclopedia
Microcycas is a genus of cycad
s in the family Zamiaceae
containing only one species, Microcycas calocoma, endemic to a small area in western Cuba
in Pinar del Río Province
.
The plant grows up to 10 m tall with an upright, sometimes branching trunk that grows to 30-60 cm in diameter. The leaves
are dark green and 0.6-1.2 m long. One unique character is that the leaves appear to be truncated near the apex because the middle and distal leaflets have similar lengths. The petioles
are 8-10 cm long and lack spines; the rachis
es also lack spines. Leaflet
s are light to dark green, lanceolate, articulate at the base, and leathery with an entire margin. Middle leaflets are 15-25 cm long by 0.8-1 cm wide. Male cones are cylindrical, 25-30 cm long and 5-8 cm in diameter, yellow-brown, and hairy. Seed cones are broadly cylindrical, 50-90 cm long and 13-16 cm in diameter, yellow-brown, and hairy. The sporophyll
s have two round apical projections. The elliptical seed
s are pink or red in color, 3.5-4 cm long and 2-2.5 cm in diameter.
The species is critically endangered, with a world population of only about 600 plants. In its native range, M. calocoma grows in small groups of 10-50 plants in montane forests at 85-250 m elevation. It also grows on the slopes of gullies and in open grassland and scrub at 50 m altitude. Soil types range from alkaline loam developed on limestone
to acidic clays containing silica. In many of these groups of plants, however, the sex ratio
is very unbalanced, resulting in a low output of seedlings. Humans have negatively impacted the species through forestry operations, clearing of land, and pesticide use. Because of the plant's graceful and ornamental appearance, harvesting of plants and seeds by growers has also seriously affected M. calocoma. Many populations are now protected in reserves.
Although M. calocomas round crown and shiny drooping leaves make it a very ornamental plant, cultivation is limited due to the lack of growing material. Locals have used the plant's toxic roots as a rat poison.
Cycad
Cycads are seed plants typically characterized by a stout and woody trunk with a crown of large, hard and stiff, evergreen leaves. They usually have pinnate leaves. The individual plants are either all male or all female . Cycads vary in size from having a trunk that is only a few centimeters...
s in the family Zamiaceae
Zamiaceae
The Zamiaceae are a family of cycads that are superficially palm or fern-like. They are divided into two subfamilies with eight genera and about 150 species in the tropical and warm temperate regions of Africa, Australia and North and South America....
containing only one species, Microcycas calocoma, endemic to a small area in western Cuba
Cuba
The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...
in Pinar del Río Province
Pinar del Río Province
Pinar del Río is one of the provinces of Cuba. It is at the western end of the island of Cuba.-Geography:The Pinar del Río province is Cuba's westernmost province and contains one of Cuba's three main mountain ranges, the Cordillera de Guaniguanico, divided into the easterly Sierra del Rosario and...
.
The plant grows up to 10 m tall with an upright, sometimes branching trunk that grows to 30-60 cm in diameter. The leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are dark green and 0.6-1.2 m long. One unique character is that the leaves appear to be truncated near the apex because the middle and distal leaflets have similar lengths. The petioles
Petiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
are 8-10 cm long and lack spines; the rachis
Rachis
Rachis is a biological term for a main axis or "shaft".-In zoology:In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually form the supporting axis of the body and is then called the spine or vertebral column...
es also lack spines. Leaflet
Leaflet
A leaflet in botany is a part of a compound leaf. A leaflet may resemble an entire leaf, but it is not borne on a stem as a leaf is, but rather on a vein of the whole leaf. Compound leaves are common in many plant families...
s are light to dark green, lanceolate, articulate at the base, and leathery with an entire margin. Middle leaflets are 15-25 cm long by 0.8-1 cm wide. Male cones are cylindrical, 25-30 cm long and 5-8 cm in diameter, yellow-brown, and hairy. Seed cones are broadly cylindrical, 50-90 cm long and 13-16 cm in diameter, yellow-brown, and hairy. The sporophyll
Sporophyll
A sporophyll is a leaf that bears sporangia. Both microphylls and megaphylls can be sporophylls. In heterosporous plants, sporophylls bear either megasporangia , or microsporangia...
s have two round apical projections. The elliptical seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s are pink or red in color, 3.5-4 cm long and 2-2.5 cm in diameter.
The species is critically endangered, with a world population of only about 600 plants. In its native range, M. calocoma grows in small groups of 10-50 plants in montane forests at 85-250 m elevation. It also grows on the slopes of gullies and in open grassland and scrub at 50 m altitude. Soil types range from alkaline loam developed on limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
to acidic clays containing silica. In many of these groups of plants, however, the sex ratio
Sex ratio
Sex ratio is the ratio of males to females in a population. The primary sex ratio is the ratio at the time of conception, secondary sex ratio is the ratio at time of birth, and tertiary sex ratio is the ratio of mature organisms....
is very unbalanced, resulting in a low output of seedlings. Humans have negatively impacted the species through forestry operations, clearing of land, and pesticide use. Because of the plant's graceful and ornamental appearance, harvesting of plants and seeds by growers has also seriously affected M. calocoma. Many populations are now protected in reserves.
Although M. calocomas round crown and shiny drooping leaves make it a very ornamental plant, cultivation is limited due to the lack of growing material. Locals have used the plant's toxic roots as a rat poison.