312 
GKNERA. 
Ephedra, L. 
Gnetum, L. 
Gnemon, Rumf. 
Thoa, Aubl. 
Abutua, Lour. 
Order CCXXIX. CYCADACEiE. 
CYCADEiE, Rich, in Pers. Synops. 2. 630. (1807) ; Brown Prodr. 346, (1810) ; Kunth in 
Humb. et Bonpl. Nov. Gen. et Sp. 2. 1. (1817) ; Synops. 1. 349. (1822) ; R. Brown 
in King’s Voyage, (1825) ; Rich. Memoir e, 195. (1826) ; Ad. Brongniart in Ann. des 
Sc. 16. 589. (1829). 
Essential Character. — Flowers dioecious, terminal. Males monandrous, naked, col- 
lected in cones ; each floret consisting of a single scale (or anther) bearing the pollen on 
its under surface in 2-valved cases which adhere in clusters of 2, 3, or 4. Females either 
collected in cones, or surrounding the central bud in the form of contracted leaves without 
pinnae, bearing the ovules on their margins. Ovules solitary, naked, with no other pericarp 
than the scale or contracted leaf upon which they are seated. Embryo in the midst of 
fleshy or horny albumen ; the radicle next the apex of the seed, from which it hangs by a 
long funiculus with which it has an organic connexion. — Trees, with a simple cylindrical 
trunk, increasing by the development of a single terminal bud, and covered by the scaly 
bases of the leaves ; the wood consisting of concentric circles, the cellular zones between 
which are exceedingly loose, the ligneous tissue having the tubes marked by circular disks. 
Leaves pinnated, not articulated, having a gyrate vernation. 
Affinities. One of the botanists who originally noticed the plants that 
constitute this order referred them to the Fern tribe ; an opinion to which 
Linnseus, having first adopted the idea of Adanson that they were related to 
Palms, finally acceded. He was followed by other botanists, until, after some 
suggestions by Ventenat that the genera Cycas and Zamia ought to form a 
particular tribe, the present order was finally characterised by the late L. C. 
Richard in Persoon’s Si/no])sis, in 1807, with the observation that it was in- 
termediate between Ferns and Palms. The opinion of their affinity to Ferns 
seems to have been thus generally adopted in consequence of their striking 
resemblance in the mode of developing their leaves ; but the supposed rela- 
tion to Palms was suggested rather by a vague notion of some -general re- 
semblance, as, for instance, in their cylindrical trunks, than by any precise 
knowledge of the structure of Cycadacese. It is only within a few years that 
a more accurate knowledge of their structure has determined the real nature 
of their affinities. In 1825, the publication of Brown’s remarks upon the 
ovule, in which he demonstrated the similarity of conformation between the 
flowers of Cycadacese and Coniferse, suggested new ideas of the affinities of 
both tribes; and the determination, in 1829, by Adolphe Brongniart, of the 
resemblance between these two tribes in the structure of the vessels of their 
wood, while it decided the near relation of Coniferse and Cycadacese, confirmed 
the proximity of the latter to Ferns, and shewed the inaccuracy of the ideas 
formerly held of a close resemblance between the latter and Palms. As this 
is still a matter but ill understood in general, it may be useful to make some 
further remarks upon the subject. 
It has been said that the dissimilarity between Cycadacese and Coniferse is 
such as to render it impossible to admit of their close approximation in any 
natural arrangement ; and that the affinity of Cycadacese being with Palms, 
the former must necessarily be widely apart from Firs. These views of the 
subject appear to have arisen either from an imperfect knowledge of the real 
