Cycas seemannii
Cycas seemannii
Safety & Hazards
The plants contain alkaloids of carcinogens and also an amino-acid that causes chronic nervous disorders[1]. Regular consumption of the plant leads to severe health problems and death. This toxic principle can be removed if the food is properly prepared but consumption of the plant still cannot be recommended because its use often means the death of the plant.
Cultivation Details
Cycas seemannii is not tolerant of frosts, other than occasional light frosts. It grows in an area where the minimum-maximum temperature range is 16 - 31°c and the mean annual rainfall is 1,875mm[2]. Succeeds in full sun or in light shade[3]. Prefers a sandy, well-drained soil[3]. Grows best in a position sheltered from cold winds[2]. A neutral soil (pH 7), is generally best for most species of cycads and allows the proper absorption of nutrients. A slightly acid soil is better for most cycads than a basic one[2]. Species in this genus can usually be transplanted easily even when quite large. The best time for moving them is just before the beginning of a new growing season, the roots being trimmed if they are damaged and perhaps some leaves being removed. New roots should develop quickly as the season progresses[2]. Species in this genus form structures known as coralloid roots. These roots branch off from the taproot or secondary roots and are distinctive in that they grow laterally or upward, forming a nodular mass at the apex. These coralloid roots occur slightly below or slightly above the soil surface and generally contain cyanobacteria, also known as blue-green algae. These are able to fix atmospheric nitrogen and make it available as a nutrient to the plant. The ability to extract this important nutrient from the air explains how many cycad species are able to survive on almost sterile soils[2]. A dioecious species, with individual plants producing either all male or all female cones. Therefore both male and female forms of the plant need to be grown if seed is required[2]. On very rare occasions, usually when a plant has been under severe stress, it can change sex and produce either all female or all male cones[2].
Propagation
Seeds - best sown as soon as they are ripe, though the seeds of many species will take a few months to finish maturing the embryo before they are ready to germinate. Sow the seeds in a tray in a freely-draining medium and place in moderate shade. Bottom heat at about 27°c will hasten seed germination dramatically. Young roots are quite brittle and once germination takes place, the root grows rapidly. It is important to pot up the seedlings at this time in order to give them enough root-space. Grow on the plants in pots until large enough to plant out[2]. Division of off-sets or suckers is best carried out just before the plant comes in to new growth at the start of the growing season[2]. Cite as: Tropical Plants Database, Ken Fern. tropical.theferns.info. 2026-02-20. <tropical.theferns.info/viewtropical.php?id=Cycas+seemannii>
Pollinators
Insects
References
- [1]The New RHS Dictionary of Gardening. 1992. — Huxley. A. · MacMillan Press · 1992 · ISBN 0-333-47494-5 ↩︎Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
- [2]The Cycads — Whitelock L.M. · Timber Press; Portland, Oregon · 2002 · ISBN 0-88192-522-5 ↩︎An excellent book dealing with the eleven different genera and almost 300 species of plants we know as Cycads. There are detailed descriptions and a host of other information for each species.
- [3]Palm and Cycad Societies of Australia. — http://www.pacsoa.org.au/ ↩︎Contains at least a little information on the majority of palm and cycad species, plus a wealth of photographs. A first class website.
- [4]Agroforestry in the Pacific Islands: Systems for Sustainability — W.C. Clarke and R.R. Thaman (Editors) · United Nations University Press, Tokyo · 1993 · http://www.unu.edu/unupress/unupbooks/80824e/80824E00.htm#Contents · ISBN 92-808-0824-9 ↩︎The guide includes information on 100 species of plants for Agroforestry. It is also available on the web at the address given above.
- [5]Flora Vitiensis Nova — Smith. A.C. · Pacific Tropical Botanical Garden; Hawaii · 1979 · http://www.biodiversitylibrary.org ↩︎A comprehensive flora of Fiji, often showing plant uses. It can be downloaded from the Internet.
- [6]IUCN Red List of Threatened Species — http://www.iucnredlist.org/ ↩︎A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.
- [7]The Cycad Pages — Royal Botanic Gardens, Sydney. · 2012 · http://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/wlist.html ↩︎A website dedicated to the various species of Cycad, with a comprehensive description of all the known species (as of 2012). At present (2015), the site is still running but is no longer being updated
- [8]Simmons' Manual of Fruit. — Simmons A. E. · David & Charles; Newton Abbot. · 1978 · ISBN 0-7153-7607-1 ↩︎A good guide to some of the cultivars of temperate fruits. It covers quite a wide range of fruits.