''Microcycas'' is a genus of

cycad Cycads are seed plants that typically have a stout and woody (ligneous) trunk (botany), trunk with a crown (botany), crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants o ...

s in the family Zamiaceae containing only one species, ''Microcycas calocoma'', endemic to a small area in western

Cuba Cuba, officially the Republic of Cuba, is an island country, comprising the island of Cuba (largest island), Isla de la Juventud, and List of islands of Cuba, 4,195 islands, islets and cays surrounding the main island. It is located where the ...

Pinar del Río Province The Pinar del Río Province is one of the 15 provinces of Cuba. It is at the western end of the island of Cuba. The capital and largest city is Pinar del Río (191,081 pop. in 2022). Geography The Pinar del Río province is Cuba's westernmost p ...

. It is estimated that there are 50-249 mature individuals left in the wild.

Description

The plant grows up to 10 m tall with an upright, sometimes branching trunk that grows to 30–60 cm in diameter. The

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

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 In biology, a rachis (from the [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the ''rachi ...

es also lack spines. leaflets 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 sporophylls have two round apical projections. The elliptical

seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...

s are pink or red in color, 3.5–4 cm long and 2–2.5 cm in diameter. File:Microcycas calocoma 0zz.jpg, Plant File:Microcycas calocoma 3zz.jpg, Leaves File:Microcycas calocoma 4zz.jpg, Trunk File:Microcycas MaleDehiscentCone.jpg, Cone File:Microcycas calocoma 5zz.jpg, Trunk

Distribution

In its native range, ''Microcycas 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 is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

to acidic clays containing

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

. In many of these groups of plants, however, the

sex ratio A sex ratio is the ratio of males to females in a population. As explained by Fisher's principle, for evolutionary reasons this is typically about 1:1 in species which reproduce sexually. However, many species deviate from an even sex ratio, ei ...

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.

Conservation

The species is critically endangered, with a world population of only about 600 plants. It is listed under

CITES Appendix I CITES (shorter acronym for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of inte ...

which prohibits international trade in specimens of this species except when the purpose of the import is not commercial, for instance for scientific research. Although ''Microcycas calocoma''s 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.

Threats

Habitat destruction and fragmentation have a moderate impact on the plants, along with the issue of over-collecting them from their natural environment. There is also a potential concern about reproductive failure due to the extinction of pollinators, although further verification is required to confirm this.

References

*Jones, David L. ''Cycads of the World: Ancient Plants in Today's Landscape''. Washington, D.C.: Smithsonian Institution Press, 2002. .
''Microcycas calocoma'' in The Cycad Pages
{{Taxonbar, from=Q1057029 Zamiaceae Endemic flora of Cuba Trees of Cuba Monotypic gymnosperm genera Critically endangered flora of North America Plants described in 1868