LICHENS. 245 
vegetative body in these is best compared to the foliage-leaves of the Curled Mint, 
with their corrugated or sinuate margins, or to those of Malva rotundifolia. It 
may also be described as a number of lobes radiating irregularly and bifurcating 
repeatedly, and only lightly joined to the substratum by root-like fringes, and there- 
fore capable of being readily loosened and detached. The light-grey Parmelia 
saxatilis, which bear brown saucer-shaped fructifications, may be taken as a repre- 
sentative of these Foliaceous Lichens. The Fruticose Lichens are distinguished as a 
third group in which the thallus rises from the ground in the shape of a shrub, 
whilst the cylindrical, fistular, and ligulate stemlets, which ramify profusely, are 
only adherent to the substratum by a very small surface at the base. With these 
are associated the Beard Lichens, which hang down from the bark of old trees in 
the form of pale, eopiously-branched filaments. Lastly, there is a fifth group, the 
Fig. 58.—Fruticose and Foliaceous Lichens. 
1 Stereocaulon ramulosum in conjunction with Scytonema; x650. 2% Cladonia furcata with Protococeus; «950 
3 Coccocarpia molybdea; section, x 650 (after Bornet). 
Gelatinous Lichens, which when moistened look like dark, olive-green, or almost 
black lumps of wrinkled and wavy jelly or as if composed of variously-divided 
bands and strips packed together into little cushions. 
In the gelatinous expansions last mentioned the algal cells are arranged in 
moniliform rows and are interwoven with the hyphal filaments of the fungus 
throughout the entire thickness of the thallus, as in Collema pulposwm (see 
fig. 57° and 57°), or else they form regular ribbon-shaped double rows, interwoven 
with few hyphe, as in Ephebe Kerneri (see fig. 571). In crustaceous, foliaceous, 
and fruticose lichens, the algal cells constitute a disorderly heap and are crowded 
together in the middle stratum of the thallus, where they are imbedded between 
an upper and a lower layer of densely felted hyphal threads, as in Coccocarpia 
molybdea (fig. 58°). 
Seeing the wide distribution of lichens it must be assumed that both partners 
occurring in the lichen-thallus are able to range about with extraordinary ease and 
latitude. When one observes how patches of the most various lichens are produced 
in a few years after a laudslip on the freshly-broken surfaces of the stones which 
