154 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
STICTA Ach. Lich. Suec. 3, 156, 257. 1798. 
Puate 26. 
The thallus is foliose, commonly lobed and prostrate on the substratum, to which 
it is attached by rhizoids. The color is usually sea-green, yellowish, or brown. The 
cortex is developed both above and below, and the upper cortex is usually thicker 
than the lower. Underneath the lower cortex extend the rhizoids, and there are 
cyphelle or naked spots on the lower side in most of the species. The medullary and 
algal layers occupy the usual positions. The algal symbiont is the common Cystococ- 
cus or probably Dactylococcus in the larger number of species. The genus has been 
variously divided, but there is scarcely any basis for such division at present and 
can not be until the plants included have been more thoroughly studied. The thallus 
is frequently pustulate, but the pustules are not conspicuous and they extend down- 
ward instead of upward as in Umbilicaria pustulata, thus forming a series of depres- 
sions which give the upper surface a reticulate appearance. 
The apothecia are rather rare and are sessile on the upper surface, or are marginal 
or submarginal. The alg of the thalloid margin sometimes die, in which case the 
margin appears externally to be lecideoid, or the margin may be overgrown by the 
apothecium and thus disappear. The hypothecium sometimes shows two distinct 
layers, the upper a network of mostly vertical hyphz and the lower a pseudocel- 
lular layer, formed of gelatinized hyphe extending for the most part horizontally. 
The cellular nature of the lower layer is by no means constant. The color is usually 
pale brownish. The paraphyses are usually simple and the apices thickened and 
brownish. The spores are 2 to 4-celled and hyaline or brown, or only very slightly 
colored. ‘Their form is spindle-shaped or acicular. 
The genus is somewhat closely related to members of the next family. 
Seven species are found in the State. 
Type species Sticta sylvatica Ach. loc. cit. 
EXPLANATION OF PLATE 26.—Fig. 1, a section of the thallus of a Sticta; e, a cyphella composed of 
a network of hyph- and protruding from an opening in the lower cortex of the thallus. Fig. 2, the form 
of cyphella found in Sticta damaecornis, consisting of a depression in the lower side of the thallus and 
surrounded by hyphe composed of almost spherical cells. In figs. 1 and 2 the usual layers of the thallus are 
also shown; a, the dermis; b, the upper cortex; c, the algal layer; d, the lower cortex; between c and d, the 
medullary layer; /, the rhizoids. Figs. 1 and 2 enlarged 400 diameters. From Schneider. 
KEY TO THE SPECIES. 
Thallus without either cyphelle or white spots below............ 1. 
S. amplissima. 
Thallus having either cyphelle or white spots below. 
Thallus having white spots below. 
Thallus lobes long and frequently truncate............ 2. 8S. pulmonaria. 
Thallus lobes short and rounded........--.---.---.---- 7. S. scrobiculata. 
Thallus having cyphelle below. 
Cyphelle sorediiform; thallus sea-green to brownish, 
often having yellowish green soredia above........-- 3. S. crocata. 
Cyphelle not sorediiform. 
Cyphellee concave, 
Thallus brown or lead-colored, clothed above 
with blackish granules .................... 5. 8S. fuliginosa., 
Thallus as above, only not clothed with 
gpranules.............2..-0-2200022-2eeee eee 4. 8. limbata. 
Cyphelle urceolate; thallus brown, varying toward 
sea-green, more or less isidioid-granulose, espe- 
cially toward the margin............-....---.--- 6. S. quercizans. 
