4 i 6 QUZMANIA 
Guzmania Ruiz et Pav. Eromeliaceae (4). 5 sp. trop. S. Am. Epi- 
phytes. 
Gymnadenla R. Br. = Habenaria Willd. (specific names mostly the 
same). 
Gymnanthes Sw. Euphorbiaceae (a, 11. 7). 10 sp. trop. Am., W. Ind. 
Gymnema R. Br. Asclepiadaceae (n. 4). 25 sp. W. Afr. to Austr. 
The leaves of G. sylvestre R. Br. contain gymnemic acid, and when 
chewed temporarily destroy the capacity of tasting sugar. 
Gymnocladus Lam. Leguminosae (11. 7). 2 sp. China and N. Am. 
Gymnogramme Desv. Polypodiaceae. 90 sp., esp. trop. G. lepto - 
phylla Desv., an annual fern, occurs in Jersey. 
Gymnospermae. One of the two great divisions of Spermaphyta or 
seed- plants. They are distinguished from the Angiospermae by the 
fact that the cpls. are not so infolded or united as to form an ovary 
round the ovules ; also the endosperm (female prothallus) is formed 
before fertilisation. The existing G. are divided into four great 
classes, Cycads, Ginkgoales, Conifers, and Gnetales. These differ 
very much from one another, so much so that it is by no means 
impossible that the class of Gymnosperms is polyphyletic (p. 30). 
The Cycads if traced backwards show a maximum in the Jurassic 
period with the great class of Cycadophyta, decreasing until about 
the end of the Eocene they had shrunk to their present size. They 
begin about the Permian period, about which time the great class of 
the Pteridospermeae, or seed-bearing ferns (the bulk of what used to 
be regarded as true ferns in the coal-measures, &c.) was dying out, 
and show considerable relationship to the latter. Some of the fossil 
forms have actual hermaphrodite firs, with numerous sta., and it is 
quite possible that these are on the direct line of ascent to the 
Angiosperms. From what the Coniferae and Ginkgoales, which 
are first found about the beginning of the Permian period, took 
their rise, is as yet quite uncertain, while we do not know enough 
about the Gnetaceae to draw many conclusions about them. 
The firs, in most Cycads and Conifers take the form of cones, and 
whether each cone represents a fir. or an infl. is still a disputed point. 
The sta. is of simple structure; in the Cycads there are several pollen- 
sacs, looking like the sporangia of Marattiaceae, on the lower side of 
a leaf-like organ ; in the Conifers the sta. has usually fewer pollen-sacs 
and is more leaf-like, while in the Gnetaceae the anthers are sessile. 
The ovules are always naked in the sense of not being enclosed in an 
ovary formed of one or more hollow cpls., but they are usually pro- 
tected in some way from the weather. Wind-pollination occurs. 
In the Cycads a considerable mass of sporogenous tissue is formed 
in the ovule (mega-sporangium) ; one of the cells of this tissue gives 
rise to the embryo-sac (mega-spore). This behaviour is closely com- 
parable to that of the higher Pteridophyta. In the embryo-sac the 
female prothallus (endosperm) forms by cell-division, and arcliegonia 
