TAXONOMY 
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differentiated into stem-bud, first leaf, root, and foot. The foot 
obtains nourishment from the prothallus until the root grows into 
the soil, when it atrophies, and the sporophyte becomes independent. 
Unequal growth and division of labor continue until a highly differ- 
entiated sporophyte results, the mature “fern plant.” 
ORDER 1. — FILIC ALES OR TRUE FERNS (HOMOSPOROUS) 
Family Polypodiaceoz. — Sporangia with annulus vertical and 
incomplete. 
The rhizomes and stipes of Dryopteris filix-mas and Dryopteris mar- 
ginalis are official in the U. S. P. The fibro-vascular bundles of 
these are concentric in type but differ from the concentric fibro- 
vascular bundles of some monocotyledons in that xylem is inner- 
most and phloem surrounds the xylem. 
ORDER 2.— HYDROPTERALES OR WATER FERNS 
(HETEROSPOROUS) 
Family Salviniacece. Floating ferns with broad floating leaves and 
submerged dissected leaves which bear sporocarps. Examples: Sal- 
vinia and Azolla. 
DIVSIOIN IV.— SPERMATOPHYTA (PHANEROGAMIA) 
Plants producing real flowers and seeds. The highest evolved 
division of the vegetable kingdom. 
SUBDIVISION I. — GYMNOSPERM/E — THE GYMNOSPERMS 
The Gymnosperms comprise an ancient and historic group of seed 
plants which were more numerous in the Triassic and Carboniferous 
periods than now. They differ from the Angiosperms in several 
respects, viz. : they bear naked ovules on the edges or flat surfaces 
of leaves called carpels, while Angiosperms bear covered ones; each 
megaspore produces within itself a bulky prothallus, in the upper 
portion of which originate one or more archegonia, while in Angio- 
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