TAXONOMY 
283 
SUBDIVISION I.—HEPATICiE OR LIVERWORTS 
Plants of aquatic or terrestial habit whose bodies consist of a 
rather flat, furchate branching thallus or leafy branch which is 
dorsoventral (having distinct upper and lower surface); the upper 
surface consists of several layers of cells containing chlorophyll, 
which gives the green color to the plants; the lower surface gives 
origin to hair-like outgrowths of the epidermal cells serving as absorp¬ 
tive parts and called rhizoids. Upon the dorsal surface of this thal- 
loid body (the gametophyte) cup-like structures are produced called 
cupules which contain special reproductive bodies called gemma , 
these being able to develop into new gametophytes. The sex organs 
are of two kinds, male and female. The male organs are termed 
antheridia, the female, archegonia. The antheridia are more or less 
club-shaped, somewhat stalked organs consisting of an outer layer of 
sterile cells investing a mass of sperm mother-cells from which are 
formed the spirally curved biciliate antherozoids, or male sexual cells. 
The archegonia are flask-shaped organs consisting of an investing 
layer of sterile cells surrounding an axile row of cells, the neck-canal 
cells, ventral-canal cells and the egg or female sexual cells. Every 
cell of the axial row breaks down in the process of maturation with 
the exception of the egg which remains in the basal portion. Both 
antheridia and archegonia generally arise on special stalks above the 
dorsal surface. After the egg is fertilized by a antherozoid, the 
young embryo resulting grows into a sporogonium (the sporophyte) 
consisting of a stalk portion partly imbedded in the archegonium 
surmounting a sporangium or capsule in which spores are produced. 
When mature the capsule splits open discharging the spores. The 
spores on germination develop into a protonema or filamentous 
outgrowth which later develops the thallus. 
Order 1.—Marchantiales, including Marchantia and Riccia . 
Order 2.—Jungermanniales, the leafy liverworts, including 
Porella. 
Order 3.—Anthocerotales, having the most complex sporo¬ 
phyte generations among liverworts, including Anthoceros, and 
M egaceros. 
