Special Morphology and Classification. 35% 
small plants; whereas, in past geological epochs, plants belonging to 
this class, as Lepidodendron, attained a height of 30, and a diameter 
of one metre. The only European genera are Lycopodium, Seaginella, 
and /soétes. _The yellow spores of several species of Lycopodium, 1. 
clavatum, annotinum, and Selago are officinal, and are used for making 
artificial lightning. [Several species are commonly known as ‘ stag’s- 
horn-moss ’ or ‘ club-moss.’] 
FLOWERING’ PLANTS. 
Cuiass XII. Gymnosperme. 
[The main characteristic of Gymnosperms, as distin- 
guished from the other classes of Flowering Plants, consists 
in the absence of an ovary, the seeds being borne naked on 
the upper side of the woody scales which some consider to 
be the carpels. With this is necessarily connected a dif- 
ference in the mode of fertilisation and in the structure of 
the pollen-grains, which has already been explained (p. 191). 
In their reproductive organs, therefore, the Gymnosperms 
exhibit a decidedly lower type of organisation than Mono-- 
cotyledons or Dicotyledons, and in many respects occupy 
an intermediate position between these classes and Cryp- 
togams. The pollen-grains suggest a homology with the 
microspores of Se/agenella ; and the corpuscula or secondary 
embryo-sacs with the central cell of the archegonia in Vas- 
cular Cryptogams. In the anatomical structure of the wood 
Gymnosperms resemble Dicotyledons. in all essential par- 
ticulars (see p. 356).] The class is divided into three 
orders :— 
Order 1. CYCADE&, The Cycadez (Fig. 453) are all tropical trees 
with simple stems, resembling Palms in their habit and Fernsin the mode 
of development of their leaves. Their columnar stems attain a consider- 
able diameter, are tuberous or globular when young, and often even 
at a later period, and bear two kinds of leaves; the one dry brown, 
hairy, sessile scales of a coriaceous texture and comparatively small 
size, the other large, stalked, simply pinnate foliage-leaves. They are 
