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Zamia is a genus of cycad of the family Zamiaceae, native to North America from the United States (in Georgia and Florida) throughout the West Indies, Central America, and South America as far south as Bolivia. Kew World Checklist of Selected Plant FamiliesHill, K.D. & Stevenson, D.W. (1999). A world list of Cycads, 1999. Excelsa 19: 67-72. Flora of North America, vol 2, Zamia integrifolia Linnaeus f. in Aiton, Hort. Kew. 3: 478. 1789. Standley, P. C. & J. A. Steyermark. 1958. Cycadaceae. In Standley, P.C. & Steyermark, J.A. (Eds), Flora of Guatemala - Part I. Fieldiana, Bot. 24(1): 11–20. The genus is considered to be the most ecologically and morphologically diverse of the cycads, and is estimated to have originated about 68.3 million years ago.
Like all Zamiaceae, Zamia plants have "coralloid" (coral-shaped) roots which host nitrogen-fixing cyanobacteria. Stems are in diameter, and when arboreal, up to tall. Leaves vary from 2 to up to 15 in number, and have an even number (5 to 60 pairs) of leaflets. petioles (leaf stalks) and rachis (leaf axis, to which leaflets are attached) may be smooth, or have prickles on the petiole and lower part of the rachis. Leaflets are linear to ovate and may be directly attached to the rachis, or may be on short petiolules. The edges of leaflets may be smooth, or may be toothed partly or around the whole leaflet. The morphology of leaflets is highly varied between even closely related species of Zamia, and within species and even within populations of a species. Studies have found that the amount of sun a plant is exposed to is responsible for differences in leaflet length, width, surface area, width ratio, shape, and density and thickness of leaflets. There is also significant morphological variation in leaflets between male and female plants in some species.
Seed-dispersal in Zamia is poorly documented for most species, but there are reports of birds and/or small to medium-sized mammals dispersing the seeds of a few Zamia species.
Pollen occurs in sticky clumps in the male cones. The clumps are broken up when Pharaxonotha beetles feed on them, scattering pollen grains throughout the interiors of the cone. Both Pharaxonotha and Rhopalotria adults, if present, become covered with pollen grains and then move to a female cone. As the beetles crawl around in female cones, a droplet at the tip of each micropyle (an opening into the ovule which will produce a seed) can capture a pollen grain as a beetle crawls past.
The reproductive cones of cycads, including Zamia, emit combinations of volatiles that produce a distinctive odor. The odors may be distinctive for each species of Zamia, or for each species of pollinator. Male and female cones of a particular Zamia species emit nearly identical odors, although the odor produced by female cones is usually weaker than that produced by the male cones of the same species. The emission of odors is enhanced by the thermogenetic heating of the cones, and the movement of pollinating beetles between cones correlates with changes in temperature and odor level.
Pharaxonotha and Rhopalotria beetles associated with Zamia species have receptors for infrared radiation on their antennae, by which they appear to detect the elevated temperature of the cones on Zamia plants. Beetles have been observed moving to cones on male plants when the cone's temperature is elevated, crawling into openings in the cone and emerging covered with pollen, and then moving to the cones on female plants when their temperature is elevated, again crawling into openings in the cone, presumably transferring the pollen.
Many of the Zamia species are, or have been, gathered to process the stem and/or seeds into starch for use as food or laundry starch, or for use as traditional medicine. Since almost the entire plant is very toxic, the starch must be grated and repeatedly washed to remove the toxins and make the starch edible. Only the sarcotesta, the pulpy covering of the seeds, is relatively free of toxins.
Consumption of cycads by livestock has resulted in two forms of cycad toxicosis. Hepato-gastrointestinal toxicosis results from damage to the liver and gastrointestinal tracts of affected animals causing depression, anorexia, and weight loss. Neurologic toxicosis, known as Zamia staggers, is the result of damage to brain, spinal cord, and dorsal root ganglia tissue causing weight loss, swaying of hind quarters, and weakness and other defects in rear limbs.
The known host dependencies of Eumaeus species on Zamia species include: Species in the Florida/Caribbean Clade are hosts for caterpillars of Eumaeus atala. Species in the Fischeri Clade, and Z. cremnophila of the Mega-Mexico A sub-clade, are hosts for caterpillars of E. childrenae. Some species in the Z. loddigesii species complex of the Mega-Mexico A sub-clade are hosts for caterpillars of Eumaeus toxea. Many species in the South American West of the Andes Clade are hosts for caterpillars of Eumaeus godartii. Several species in the South American East of the Andes Clade are hosts for caterpillars of Eumaeus minyas. One Zamia species found east of the Andes, Z. poeppigiana, is host for caterpillars of both E. minyas and Eumaeus toxana. Another Zamia species east of the Andes, Zamia amazonum, also hosts caterpillars of E. toxana. The use of other Zamia species as hosts for Eumaeus species had not been established as of 2023.
Caterpillars of the moths Seirarctia echo and Anatrachyntis badia have also been observed on Zamia integrifolia, and caterpillars of an unknown species of a Blastobasidae moth have been observed on Zamia pumila.
Despite the ancient history of cycads, species diversity in Zamia is geologically recent. Calonje et al. found a stem age for Zamia of 68.28 million years ago (mya), and a Crown group age of 9.54 mya.
Zonneveld and Lindström (2016) measured genome size in 71 species of Zamia and found support for three geographical groupings. Variation in genome size of Zamia species is fairly small compared to many other genera, with the ratio of largest to smallest just 1.36, but the authors found significant differences in genome sizes between three geographical areas. Species in Mega Mexico, including the northern part of Central America, had the largest average genome size. Species in South America, plus Costa Rica and Panama, had the smallest average genome size, while species in the West Indies and Florida had an intermediate genome size.
Calonje, et al. (2019) analyzed the DNA from 70 species of Zamia, finding support for four geographically distinct (plus a single isolated species). A clade including the species found on the Caribbean islands and in Florida is Sister group to the rest of the genus. The species of the Caribbean clade have diverged within the last 1.9 million years. The Mesoamerica clade includes all species found in Mesoamerica (north of Nicaragua), except for the single species Z. soconuscensis. It has a divergence age of 5.79 mya. The Isthmus clade includes species found in southernmost Nicaragua, Costa Rica. Panama, and northernmost Colombia, and has a divergence age of 2.35 mya. The species in South America form another clade, which is sister to the Isthmus clade. It has a divergence age of 2.62 mya.
Lindstrom et al. (2024) analyzed from 77 species of Zamia finding support for seven clades of the genus occupying distinct geographical ranges. Clade I is a strongly monophyletic clade that includes eight of the species of the Caribbean islands and Florida. Clade II (the Fischeri clade), consists of three species found in Veracruz, Hidalgo, Querétaro, San Luis Potosí, and Tamaulipas states in Mexico. This clade is a sister to Clade I, with the group of Clade I and Clade II being sister to the rest of the genus. Clade III (Mega Mexico) is divided into the sub-clades III-A and III-B. Clade III-A includes 14 species found in Mexico and northern Central America. Clade III-B consists of seven species found in Honduras, Guatemala, and Belize. Clade IV consists of the single species Z. soconuscensis found in Chiapas state in Mexico. Clade V (the Isthmus clade) includes 15 species found in southern Nicaragua, Costa Rica, Panama, and northern Colombia. Clade VI includes 12 species found in southernmost Panama and west of the Andes in Colombia and Ecuador. Clade VII consists of four closely related species in northern Columbia (the Manicata clade) and 13 species east of the Andes in Bolivia, Brazil, Colombia, Ecuador, Peru, and Venezuela.
A study published in 2008 proposed a Zamia katzeriana species complex, consisting of Zamia katzeriana, Z. cremnophila, Zamia lacandona, Zamia purpurea, and Zamia splendens. The 2019 Calonje et al. study found a clade of five species, called the Purpurea Clade, that included Z. cremnophila, Z. lacandona, Z. purpurea, Z. splendens, and Z. grijalvensis, which shared four species with the Zamia katzeriana species complex. Z. katzeriana itself was not included in the 2019 study. Z. grijalvensis was described in 2012, after the 2008 study that defined the species complex. All of the species in the Zamia katzeriana species complex are Endemism to Mexico.
A genetic study published in 2009 found a basis for a Zamia loddigesii species complex in the presence of the same four discrete clusters of DNA repeats in Zamia loddigesii, Zamia furfuracea, Z. picta, Zamia paucijuga, Z. polymorpha, Zamia purpurea, Zamia spartea, Zamia splendens, and Z. sylvatica. (After the study was published, Z. sylvatica was reclassified as a synonym of Z. loddigesii, Z. picta was reclassified as a synonym of Zamia variegata, and Z. polymorpha was reclassified as a synonym of Zamia prasina.) All of the species in the Zamia katzeriana species complex are found in Mexico, with three of those species being found in other countries in northern Central America.
The 2019 DNA study found a clade of seven species, the Furfuracea Clade, that included Z. furfuracea, Zamia herrerae, Z. loddigesii, Z. paucijuga, Z. prasina, Z. spartea, and Z. variegata. Six of the species in the Furfuracea Clade were also defined in the Zamia loddigesii species complex, with Z. herrerae added to the Furfuracea Clade and Z. purpurea and Z. splendens removed from it.
Zamia meermanii, which is sister to the rest of Mega Mexico A Clade in the 2024 transcriptomes study, has not been described as belonging to either the Z. katzeriana species complex or the Z. lodigessii species complex. It is endemic to Belize, and the only species in the Mega Mexico A Clade that has not been found in Mexico. The 2019 DNA study placed Z. meermani in the Tuerckheimii Clade, equivalent to the Mega-Mexico B Clade.
The 2019 DNA study found a clade of six species, the Tuerckheimii Clade, that included Z. decumbens, Z. onan-reyesii, Z. meermani, Z. sandovalii, Z. standleyi, and Z. tuerckheimii. Five of the species in the Tuerckheimii Clade were also defined in the Mega Mexico B Clade, with Z. meermani not included in the Mega Mexico B Clade and Z. monticola and Z. oreillyi added to it.
Five of the six species in the third sub-clade have previously been placed in the Zamia skinneri species complex. Z. skinneri has been regarded as a highly variable species. Z. neurophyllidia was described as a new species in 1993, based on a population of what had been regarded as a dwarf form of Z. skinneri. A study published in 2004 proposed that Z. neurophyllidia and Z. skinneri were a "hybrid species complex", and noted that Z. skinneri included several morphologically distinct populations. In 2008, three sub-populations of Z. skinneri were described as the new species Z. hamannii, Z. imperialis, and Z. nesophila. All five of the species in this complex are found in Bocas del Toro Province in Panama, at least three of the species are endemic to that province, and all of them have plicate leaves, a trait that occurs elsewhere in Zamia only in Zamia dressleri in Colon and Guna Yala (formerly San Blas) provinces in Panama, and in Zamia roezlii and Zamia wallisii in Colombia. It has been suggested that Z. skinneri is the central species of the complex, and that the other species have evolved rapidly from Z. skinneri on the periphery of its range due to geographic or other isolation. (2026). 9789535104544, InTechOpen. ISBN 9789535104544 The 2019 DNA study places the same five species in a Skinneri Clade. Both the 2019 DNA study and the 2024 transcriptomes study place Zamia lindleyi as Sister group to the Skinneri Clade.
The 2019 study defined a second Clade, the Eastern Clade, consisting of Z. encephalartoides, Zamia muricata, and Zamia lecointei. The 2024 study includes an unnamed Clade consisting of those three species plus Zamia amazonum, Zamia ulei, and Z. orinoquiensis (neither Z. ulei nor Z. orinoquiensis were included in the 2019 study). The third Clade defined in the 2019 study, the Amazonian Clade, contains Zamia amazonum, Z. poeppigiana, Zamia boliviana, Z. macrochiera, and Z. hymenophyllidia. The 2024 study includes an unnamed Clade consisting of Z. poeppigiana, Z. boliviana, Z. macrochiera, Z. hymenophyllida, Z. amazonum, and Zamia urep. Both the 2019 study and the 2024 study found a small Clade consisting of Zamia huilensis and Zamia tolimensis, which was labeled the Tolimensis Clade in the 2019 study. This Clade was found to be sister to the Eastern Clade in the 2019 study, and sister to the group consisting of the Eastern and Amazonian clades in the 2024 study.
The number of recognized species in Zamia has almost tripled since 1980. There were approximately 30 species recognized in 1980, 40 in 1988, 58 in 2008, 76 in 2016, and 80 in 2019. As of May 2025, the World List of Cycads lists 89 accepted species of Zamia, the Royal Botanic Gardens, Kew, recognizes 86, and World Flora Online recognizes 90.
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