Microcycas Calocoma

Abstract

In a recent number of the BOTANICAL GAZETTE (i) there appeared a brief taxonomic account of this plant. It was described originally by MIQUEL, from fragmentary material, as Zamia calocoma (2), although on account of its resemblance to a small Cycas revoluta he made for it the section Microcycas under Zamia. Later DECAN-DOLLE (3) added to MIQUEL's description and raised the section to generic rank. The previous paper (I) added to the knowledge of the taxonomic features of the species; while the present paper deals with the field studies and the morphology. FIELD OBSERVATIONS The region in which this study was made is in the Sierras of western Cuba, beginning with the mountains northwest of San Diego de los Bahos, running through the Santa Catalina region, and ending to the westward with the mountain known locally as Cuchillo de Pinar, near San Andrace. Within this area Microcycas was found in four places, in three of which the plants were few and distinctly local. In the other (Cuchillo de Pinar) the plants were found one, two, or a halfdozen together at infrequent intervals for a distance of one and a half to two miles along the mountain. It is highly probable that sufficient search would result in the discovery of other groups in other mountains. The native Cuban mountaineers, to some of whom the plant is known as "palma corcho," reported that they had heard of the plant elsewhere, though they said it is extremely rare. The folklore of the region says that the roots of the "palma corcho " are good for use as rat poison, hence the desirability of a knowledge of its location, and the probability that there would be knowledge of any large groups of individuals should they exist. Botanical Gazette, vol. 44] [ii8

Types of Development From the Central Nucleus of Zamia Umbrosa

“…Type C is of special interest in connecting A and 13 with C and D by showing that a morphological equivalent of the ventral canal nucleus (the upper nucleus) may continue its growth and form a large nucleus identical with the egg nucleus in outward appearances and possibly in function. We cannot follow this matter further in this paper but it should be noted that examples of plurinuclear archegonia in Microcycas have been reported by Caldwell (1907) and by Reynolds (1924); and recently Johansen (1953) has mentioned (without details or figures) the presence of "binucleate archegonia with double fertilization in lamia floridana," and plurinucleato archegonia in Ginkgo biloba.…”

“…We cannot follow this matter further in this paper but it should be noted that examples of plurinuclear archegonia in Microcycas have been reported by Caldwell (1907) and by Reynolds (1924); and recently Johansen (1953) has mentioned (without details or figures) the presence of "binucleate archegonia with double fertilization in lamia floridana," and plurinucleato archegonia in Ginkgo biloba. Type C is of special interest in connecting A and 13 with C and D by showing that a morphological equivalent of the ventral canal nucleus (the upper nucleus) may continue its growth and form a large nucleus identical with the egg nucleus in outward appearances and possibly in function.…”

Pollination of endangered Cuban cycad Microcycas calocoma (Miq.) A.DC.

“…Microycas calocoma has been cited by Caldwell (1907) as rare. Foster & San Pedro (1 942) explored 1 1 localities, with an estimation of approximately 500 individuals.…”

“…Efforts to understand the biology of this species have been related to evaluation of populations, seed production, morphology, vascular anatomy, spermatogenesis and general characteristics of its habitat (Caldwell, 1907;Dorety, 1909;Reynolds, 1924;Chrysler, 1926;Downie, 1928;Foster & San Pedro, 1942;Del Risco, Morell & Samek, 1984;Pefia-Garcia et al, 1986;1988;Norstog, 1990;Pefia-Garcia & Lopez-Garcia, 1995); little or no work has been done to elucidate its reproductive biology in the field. Pollination and natural regeneration from seed appears to be practically nil, with very few exceptions (Foster & San Pedro, 1942;Del Risco et al, 1984).…”

Growth and Development of the Male Gametophyte of Ginkgo Biloba Within the Ovule (In Vivo)

“…Among cycads, work by Webber (1901), Caldwell (1907), Lawson (1926), Downie (1928), Chamberlain(1909Chamberlain( , 1910Chamberlain( , 1912Chamberlain( , 1916Chamberlain( , 1935, Baird(1939), Brough and Taylor(1940), Swamy (1948), Rao (1961), and others indicates substantial diversity ofform. Cycad male gametophytes are unbranched or only slightly branched and all appear to undergo a pronounced and unusual growth of the proximal (pollen grain end) portion of the gametophyte late in development.…”