f _Flowerless
Plants_ is both good and convenient: for they have not flowers in the
proper sense. The essentials of flowers are stamens and pistils, giving
rise to seeds, and the essential of a seed is an embryo (8).
Cryptogamous or Flowerless plants are propagated by SPORES; and a spore
is not an embryo-plantlet, but mostly a single plant-cell (399).

483. =Vascular Cryptogams=, which compose the higher orders of this
series of plants, have stems and (usually) leaves, constructed upon the
general plan of ordinary plants; that is, they have wood (wood-cells and
vessels, 408) in the stem and leaves, in the latter as a frame work of
veins. But the lower grades, having only the more elementary cellular
structure, are called _Cellular Cryptogams_. Far the larger number of
the former are Ferns: wherefore that class has been called

484. =Pteridophyta, Pteridophytes= in English form, meaning
_Fern-plants_,--that is, Ferns and their relatives. They are mainly
Horsetails, Ferns, Club-Mosses, and various aquatics which have been
called _Hydropterides_, i. e. Water-Ferns.

485. =Horsetails=, _Equisetaceae_, is the name of a family which consists
only (among now-living plants) of _Equisetum_, the botanical name of
Horsetail and Scouring Rush. They have hollow stems, with partitions at
the nodes; the leaves consist only of a whorl of scales at each node,
these coalescent into a sheath: from the axils of these leaf-scales, in
many species, branches grow out, which are similar to the stem but on a
much smaller scale, close-jointed, and with the tips of the leaves more
apparent. At the apex of the stem appears the _fructification_, as it is
called for lack of a better term, in the form of a short spike or head.
This consists of a good number of stalked shields, bearing on their
inner or under face several wedge-shaped spore-cases. The spore-cases
when they ripen open down the inner side and discharge a great number
of green spores of a size large enough to be well seen by a hand-glass.
The spores are aided in their discharge and dissemination by four
club-shaped threads attached to one part of them. These are hygrometric:
when moist they are rolled up over the spore; when dry they straighten,
and exhibit lively movements, closing over the spore when breathed upon,
and unrolling promptly a moment after as they dry. (See Fig. 493-498.)

[Illustration: Fig. 493. Upper part of a stem of a Horsetail, Equisetum
sylvaticum. 494. Part of t