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Subspecies, varieties, forms and cultivars of plants belonging to the Cycas micholitzii group
Cycas simplicipinna, Cycas micholitzii, Cycas bifida and Cycas multipinnata forms a group. C. simplicipinna has undivided pinnae, whereas C. micholitzii and Cycas bifida have pinnae that are once dichotomous, and C. multipinnata has pinnae that are two to five times dichotomous. Thus there is a transformation series from simple to dichotomous to multidichotomous. This phenomenon becomes even more interesting when examining the development from seedling to adult of individual plants of C. micholitzii and C. multipinnata. In C. micholitzii, the first leaf has undivided pinnae, the second leaf has one dichotomous pinnae. In C. multipinnata, the first leaf has undivided pinnae, the second leaf has one dichotomous pinnae, the third through fifth leaves have a pinnae where one of the dichotomies is itself dichotomous resulting in a tripartite pinnae, and the sixth and subsequent leaves have pinnae with multiple dichotomies resulting in leaves that have a minimum of three dichotomies per pinna. Thus, we not only have a transformation series between species but also within a species.
- Cycas bifida (Dyer) K.D.Hill: has few arching fronds with long petioles shooting out of a small, dome-shaped caudex and glossy leaflets bifurcated very near to the base. Distribution: China (Guangxi, Yunnan) and northern Viet Nam (Cao Bang, Lang Son and Tuyen Quang).
- Cycas micholitzii Dyer: is mostly stemless with, erect fronds, comparatively short and narrow leaflets are bi-pinnate, in other words they split dichotomously, two or three times, giving a most un-cycad like appearance. Distribution: China, Vietnam and Laos.
- Cycas multipinnata C.J.Chen & S.Y.Yang
- Cycas simplicipinna (Smitinand) K.D.Hill: is mostly stemless with large, erect fronds with broad and well-spaced undivided leaflets, small microsporangiate cones, small megasporophylls with short spines on the apical lamina. Distribution: China,Viet Nam and Thailand.
Bibliography: Major references and further lectures
1) Barbara A. Ambrose, Michael D. Purugganan “Annual Plant Reviews, The Evolution of Plant Form” John Wiley & Sons, 21 November 2012
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