A very particular group of plants: Zamia

Cycad plants are found in tropical and subtropical areas around the world. Panama has the most diverse group of cycad plant in the Neotropics. The species found in Panama have a cylindrical trunk, with leaves that grow directly from the trunk, forming a “crown” of evergreen leaves, and a plastic texture, that sometimes could be confused with ferns or palms.

Within the forest of Bocas del Toro, we frequently find this plant defoliated by the larvae of the White-tipped Cycadian (Eumaeus godartii). The larvae can eat the entire plant, but do not kill it.

Eumaeus godartii

Larvae of the White-tipped Cycadian (Eumaeus godartii)

Cycads are gymnosperms (naked seeds), the unfertilized seeds are open to the air to be pollinated. Cones are the reproductive organs of the cycads and are composed by highly modified leaves.

Panama Flora

Female cones of a Zamia plant, at Tranquilo Bay grounds, Bastimentos Island.

Cycad plants are females or males; female cone carried ovules, and every male cone (is smaller in diameter, compared with the female) carries several pollen capsules. There are cases of cycad plants changing sex, but never producing male and female cones at the same time.

Cycad Zamia Male Cone

Male cones of a Zamia plant – Tranquilo Bay, Bastimentos Island

In the past the pollination of cycads was thought to be completed by the wind, but its been proven that it is completed by insects.

Thousands of this plant grow on the white sand beaches of Bastimentos Island.  Here it was observed and has been reported by researchers an unusual occurrence of salt water tolerance.  Cycad seeds can float in the water, allowing the plant to disperse from island to island within the archipelago – this was observed in this group of plants around 2004 in Bocas del Toro.

 

 

 

Zamia

Zamia are rare primitive plants that are regarded as living fossils. Zamia is a genus of cycad of the family Zamiaceae, containing around 50 species, native to North, Central and South America.
Cycads are found across much of the subtropical and tropical parts of the world. Though they are a minor component of the plant kingdom today, during the Jurassic period they were extremely common. Cycads are long-lived with infrequent reproduction, and most populations are small, putting them at risk of extinction from habitat destruction and stochastic environmental events. All cycads are in the CITES appendix appearing under the heading Plant Kingdom and under three family names, Cycadaceae, Stangeriaceae and Zamiaceae.

Cycads can be cut into pieces to make new plants, or by direct planting of the seeds. Propagation by seeds is the preferred method of growth, and two unique risks to their germination exist. One is that the seeds have no dormancy, so the embryo is biologically required to maintain growth and development, which means if the seed dries out, it dies. The second is that the emerging radicle and embryo can be very susceptible to fungal diseases in its early stages, when in unhygienic or excessively wet conditions. Thus, many cycad growers pregerminate the seeds in moist, sterile media such as vermiculite or perlite. However pregermination is not necessary, and many report success by directly planting the seeds in regular potting soil. As with many plants, a combination of well-drained soil, sunlight, water and nutrients will help it to prosper. Although, because of their hardy nature, cycads do not necessarily require the most tender or careful treatment, they can grow in almost any medium, including soilless ones. One of the most common causes of cycad death is from rotting stems and roots due to over-watering. While the cycads have a reputation of slow growth, it is not always well-founded, and some actually grow quite fast, achieving reproductive maturity in 2–3 years (as with some Zamia species).

There are symbiotic relationships between many of the cycads and specific insects.

Here in Bocas del Toro we have both the Zamia dressleri and the Zamia skinneri. Both are threatened by habitat loss. Both have symbiotic relationships with butterflies.

Zamia

Here is a link to an article by Alberto S. Taylor, Jody L. Haynes, Gregory Holzman and Jorge Mendieta regarding cycad conservation. This particular article is entitled “Variability of Natural Populations and Conservation Issues Facing Plicate-Leaved Zamia Species in Central and Western Panama. It is a scientific article that includes interesting information on these endangered species. http://cycadconservation.org/publications/Taylor-et-al-Zamia-Population-Variability.pdf