266 ESSENTIALS OF BOTANY 
MARCHANTIA, ONE OF THE LIVERWORTS 
342. Occurrence. — Marchantia polymorpha, the com- 
monest species of. the genus, is widely distributed in this 
country and in Europe. It is found on damp soil or rocks, 
especially in shaded places. 
348. Gross Structure. — Secure 
if possible specimens in the fruit- 
ing condition (Figs. 190, 191).? 
Examine with and without the 
magnifying glass and note: 
(a) The size, shape, and color 
of the thallus or body of the plant. 
(b) The mode of forking. 
Branches are formed in pairs on 
each side of the growing tip. Do 
they develop equally ? 
i TU 
\ \) 
AN 
Fic. 189. Vertical Section through 
a Lobe of Ricciocarpus. (Magni- 
fied.) 
a, antheridium; e, epidermis; 7, spongy 
interior of thallus with air-chambers ; 
r, bases of rhizoids. 
(c) The distinctions between 
the upper and the lower surface 
of the thallus. Look for scales 
on either surface and for rhizoids 
or root-like organs. Examine the 
upper surface with the magnify- 
ing glass and draw a portion of it, showing the diamond-shaped areas, 
each with a pore in its center. 
(d) The buds, or organs of vegetative reproduction, small struc- 
tures which, when detached, serve to produce new plants. 
(e) The male receptacles, stalked disks with scalloped margins. 
1If Marchantia cannot be easily obtained, Lunularia, a genus very com- 
mon in greenhouses, may be substituted. It is easily recognized by the cres- 
cent-shaped cups in which the reproductive buds are borne. The structure 
is rather similar to that of Marchantia and the mode of vegetative reproduc- 
tion is the same in both. Zuwnularia as found in our greenhouses does not 
undergo sexual reproduction. 
2 M. disjuncta, which is shown in these figures, differs considerably in the 
form of the receptacles from M. polymorpha. The male receptacle of the 
latter looks a good deal like the female receptacle of the former but is much 
shorter-stalked. 
