OPEGRAPHA Persoonii,
Hock Opegrapha.
CRYPTOGAMJA Algae,
Gen. Char. Seeds in blacky linear, sessile, simple or
branched,bordered clefts,in an u ninterru pted crust.
Spec. Char. Crust leprous, indeterminate, whitish.
Clefts aggregate, somewhat branched, contorted,
rugged, linear.
Syn. O p eg rap h a Persoonii, Ach. Meth. 17. Winch,
v. 2. 30.
O. rupestris. Pers. in Ust, Ann.fasc. 11. 20.
Lichen Persoonii, Ach. Prodr. 19,
(3. Ach. Meth. 17.
L. simplicis varietas. Dav. in Tr. o f Linn. Soc. v. 2 .
284.
F o u n d on calcareous rocks, or on sand-stones, granites,
and walls of various materials. Our specimen on coarse white
sand-stone was communicated by the Rev. H. Davies, and
shows both states of the species. That part in which the fructification
is most dispersed and simple, agrees with an authentic
specimen of 0. Persoonii from Acharius. The more crowded
or aggregate part is the variety j3, descrihed by Mr. Davies as
one state of his Lichen simplex, see t. 2152, from which however
it proves, now this tribe of plants is better understood,
totally distinct.
The crust is dispersed, very thin and powdery, often scarcely
discernible at ah advanced period of growth. Clefts deep
black, rather shining, elevated; sometimes scattered, short,
and very small; more frequently aggregate, or branched ; in
the abovementioned variety especially they are, as it were,
heaped together. They are twisted or wavy, rugose, with a
deeply impressed disk narrower than the margins.