Mar., 1913.] 
Caloplaca Pyracea ( Ach.) Th. Fr. 
99 
The plants of this group excrete a sticky substance by which 
insects are often captured in large numbers. 
In the Silenes, Tricuspis, Parsonsia, Polanisia and Circaea the 
secretive and absorbing glands are on the stems, while in Carduus 
the viscid substance is excreted on the bracts of the involucre. 
In this case the excretion acts more as a protection to the flower 
against crawling insects. In certain western species of Carduus 
the glutinous secretion on the bracts is so abundant that it is 
impossible for any crawling insects like ants to pass over it to the 
flowers above. The species in Ohio have the glands on the bracts 
and insects were observed adhering to them but they are much 
less prominent. 
CALOPLACA PYRACEA (ACH.) TH. FR., A CRUSTACEOUS 
LICHEN ON THE SANDSTONE SIDEWALKS OF EAST 
CLEVELAND, OHIO. 
Edo Claassen. 
Owing to the frequent rains last summer more algae seemed to 
grow on the sidewalks than ever before. They were yellowish- 
green, represented a species of Cystococcus, and occasionally 
covered the entire surface of the stones. Here and there small 
specks of a grayish color appeared on them, a fungal growth 
several mm. in diameter. The mycelium spread out and continued 
to do so while its central part began to disappear. In these centers 
algae again commenced to grow while the mycelium stretched 
out more and more, surrounding the algae like a ring continually 
increasing in size. It frequently happened that some mycelium 
located itself on the central part of this algal layer, thus apparently 
repeating the former process. It was on these layers of mycelium 
that apotheeia were forming in great numbers. They were yellow 
to orange-yellow with their rim-like external part, the so-called 
exciple, lighter in color. When young they were somewhat 
convex but later on mostly flat. 
The apotheeia contained asci in a more or less mature condi¬ 
tion. The spores were very seldom simple, except when quite 
young and filled with granular protoplasm, but usually even when 
rather young they were two-celled. Nearly fullgrown spores as 
well as ripe ones were always two-celled. Although the two- 
celled spores of this lichen are said to be generally “polar-biloc¬ 
ular,” none of this type could be ascertained in the specimens 
examined. 
All the lichen specimens were concentrically arranged on the 
stones wherever they had space enough to spread; when full 
grown their diameter reached 50 to 70 mm. or even more. In the 
central part of an examined specimen was found an algal layer of 
