Friesia IV, 1-2

-78 -
the apical septum of the prophialide is formed. Simultaneously the
falx starts being smoked as a first sign of maturing, and finally a
single conidium develops on each phialide. This whole evolution
from the starting outgrowth on the side of the hypha till the develop­
ment of the conidia, covers a period of a little more than 24 hours
at room temperature.
A culture of t he isolate has been sent to Centraalbureau voo r
Schimmelcultures, Baarn.
10. Peronospora dianthicola Barthelet(?) On September
15, 1949 Mr . F r . J e n s e n, gar derier in Havndal, J utland, sent me
a number of young diseased see dlings of D i ant hus caryophylZus f l. pl.
Triumph. The plants were heavily infected by a Peronos por a species.
This fungus genus has so far no t been observed on D i ant hus
in Denmark.
Th e patches we re found mainly on the underside of the leaves,
and they were violet to brownish gray. The conidiophores were 4-6
t ime s dichotomously branched, 250- 380 p in length (10 measuremen
ts : 315 p ), and ab. 7-11p in breadth. The conidia were 15-24
by 12.8-16.5 p (25 measurements: 19.7 by 14.7 p). Oospores were
not found.
Among a number of Peronospor a species deseribed from Caryo­
phy llaceae two species have been recorded from sp ecies of D ianthus:
Peronospora diant hi de Bary (type host: Tuni ca protdera, syn .
D ianthus prolifer) , and Peronospora dianthicola Barthelet (type
host: Dianthus caryophyZlus fl. pl.).
G a u m a n n (1923) limited the first species to inelude only
the Peronospora on Tunica proliiera, and he set up P. agrostem­
matis Gåum. for t he A grostemma form of D e B a r y's species.
Unfortunately, no measurements are given in the original diagnosis
of D e B a r y (1863, 1864), but, on the other hand, when the great
variation in the Peronospora species on Caryophyllaceae is taken
into consideration, there is no particular reason to assume that the
Danish Peronospora on Dianthus caryophylZus be identical with just
the Peronospora form recorded by D e B a r y on Tunica. P. di an­
thicola, recently set up by B a r t h e l e t (1946), has conidiophores
of 280-300p in length, conidia measuring 23.8 by 17.8p, and
oospores measuring ab. 39 Jl in diameter.
The conidia of my Peronospora material are thus considerably
smaller as far as the average size is concerned than those mentioned