310 MANUAL OF POISONOUS PLANTS 



the mucilaginous material acting as a servant to attract the sperm cells. After 

 fertilization occurs, spores develop. In addition to the sexual method of repro- 

 duction an asexual reproduction also occurs. The gametophytic and sporo- 

 phytic stage are sharply dififerentiated.. 



In the development of the sexual generation the spore germinates giving 

 rise to a tube v^^hich develops into a new plant, and is called protonema. There 

 are two divisions, the common mosses, and the liverworts. The parts of the 

 fruiting moss plant are as follows: The calyptra or membranous cap which 

 covers the capsule and soon falls off, exposing the operculum, which is a kind of 

 lid, that is also thrown off. The peristome is developed within the operculum 

 and contains teeth, between which the spores are discharged. The elaters in 

 Marchantia are for the dissemination of the spores. The peristome differs 

 in different genera ; this affords a convenient means of classification. The 

 spores are found in the capsule and running through the center is a slightly 

 differentiated tissue, the columella. In Funaria the reproductive organs occur 

 on different plants. The sexual organs are borne much like those of liver-worts 

 at the apex of the stem. The antheridia occur in a small rosette of leaves 

 and are club-shaped, the upper part consisting of a single layer of large 

 chlorophyll bearing cells in which small cubical masses occur, the biciliated 

 sperm cells. The archegonia occur in young plants and closely resemble the 

 archegonia of liverworts, except that they have a larger neck. The spore? 

 germinate by producing a protonema which early produces a rhizoid. 



The liverworts and mosses are much more highly differentiated than any 

 of the Thallophytes, being characterized by more or less differentiation into 

 tissues. Their life history presents a well marked alteration of generations. 

 The gametophyte is more conspicuous than the sporophyte ; the germinating 

 spore produces the protonema, which consists of a branched filament, the cells 

 containing the chloroplastids. The protonema is usually short-lived in the 

 Hepaticae but in the true mosses is longer-lived and may persist from year to 

 year. The moss plant is attached to the soil by small unicellular root hairs, or 

 by many curled filaments which, in mosses, are called rhizoids. The shoots of 

 mosses bear lateral organs known as leaves. In Polytrichum and Mnium the 

 leaf consists, essentially, of a single layer of cells except on the midrib. In the 

 leafy-stemmed liverworts like Frullania two rows of lateral leaves occur. In 

 Marchantia the leaves are rudimentary and occur on the under surface of the 

 thalloid structure in the form of small scales. The small dots on the surface 

 represent the stomata which are dome shaped structures consisting of a num- 

 ber of cells on each side. The stomata communicate with the photosynthetic 

 system of the plant. 



Bryophytes are divided into two classes, tlic liverworts — Hepaticae — and 

 the Mosses — Musci, the latter represented by si)agnum moss — Polytrichum, 

 Bryum, etc. 



The mosses are distingiiished from the thallophytes by their sexual repro- 

 duction, the antheridia or male organs arc stalked, ellipsoidal, or club-shaped, 

 and enclose small cubical cells, in which the ciliated sperm cells occur. These 

 are ejected, float about in the water till the female reproductive organ, the 

 archegnnium, is reached. This is a flask-shaped body containing a neck and 

 an egg cell. At maturity the upper part of the canal cells become mucilaginous, 

 the sperm cells pass down through the canal to the egg cell, where fertilization 



