416 BOTANY part ii 



The fructifications of Scleroderma vulgare (Fig. 352, 1) have a comparatively 

 simple structure. They are nearly spherical, usually about 5 cm. thick, and have 

 a thick, light brown, leathery peridium which finally becomes cracked and 

 ruptured at the apex. The gleba is black when ripe, and contains numerous 

 chambers filled with interwoven hyphae which produce lateral, pear-shaped basidia 

 with four sessile spores (Fig. .3.^2, 2). This species, which is considered poisonous, 

 is sometimes mistaken for one of the Truffle Fungi. 



The genera Bovista and Lycoperdon (Fig. 352, 3) (Puffballs) have also sjiherical 

 fructifications, which are at first white and later of a brown colour. In the last- 

 named genus they are also stalked, and in the ca.se oi Lycoperdon Bovista may even 

 become half a metre in diameter. The peridium is formed of two layers ; the outer 

 separates at maturity, while the inner dehisces at the summit. The hj-menial 

 layer of basidia, in the fungi of this group, lines the chambers of the gleba. The 

 chambers are also provided with a fibrous capillitium consisting of brown, thick- 

 walled, branched liyphae which spring from the walls, and aid in distributing the 

 spores. The fructifications are edible while still young and white. When mature 

 they contain urea which is not elsewhere found in plants. 



In the related genus Geaster (Earth-star) (Fig. 352, 4) the peridia of the nearl}^ 

 spherical fructifications are also composed of two envelopes. .When the dry fruit 

 dehisces, the outer envelope splits into several stellate segments and the inner 

 layer of the peridium becomes perforated by an apical opening. 



The highest development of the fructifications is exhibited by the Phalloideae ("•*), 

 of which Pliallus impudicus (Stink-horn) is a well-known example. This fungus 

 is usually regarded as poisonous. It was formerly employed in a salve as a 

 remedy for gout. Its fructification recalls that of the discomycetous Morchella, 

 but it has quite a different manner of development. A fructification of this 

 species of Phallus is about 15 cm. high. It has a thick, hollow stalk of a white 

 colour and is perforated with pores or chambers. Surmounting the stalk is a bell- 

 shai^ed pileus covered with a brownish-green gleba which, when ripe, is converted 

 into a slimy mass (Fig. 353). When young the fructification forms a white, egg- 

 shaped body, and is wholly enveloped by a double-walled peridium with an inter- 

 mediate gelatinous layer. Within the peruiium (also termed volva) the hyphal 

 tissue becomes differentiated into tlie axial stalk and the bell-shaped pileus, carry- 

 ing the gleba in the form of a mass of hyphal tissue, which contains the chambers 

 and basidial hymenium. At maturity the stalk becomes enormously elongated, 

 and pushing through the ruptured peridium raises the pileus with the adhering 

 gleba high above it. The gleba then deliquesces into a dropping, slini}- mass, 

 which emits a carrion-like stench serving to attract carrion-flies, by whose agenc}' 

 the spores embedded in it are disseminated. 



Class XIV 



Lichenes (Lichens) (''' '''■'^") 



The Ijichens are symbiotic organisms ; they consist of higher 

 Fungi, chiefly the Ascomycetes, more rarely Basidiomycetes, and uni- 

 cellular or filamentous Algae (Cyanophyceae or Chlorophyceae), living 

 in intimate connection, and together forming a compound thallus or 

 CONSORTIUM. Strictly speaking, both Fungi and Algae should be 

 classified in their respective orders ; but the Lichens exhibit among 



