118 Monten P. Porsio. 
searched for it in vain on the habitat mentioned. Ordinarily a hybrid- 
ation between the two species will not easily be effected, because 
P. grandiflora has ceased flowering when P. minor begins. But retarded 
flowers may sometimes be found on spots where the snow has lasted 
longer than usually. 
Although I saw but two specimens I shall mention this probable 
hybrid here, not only to call the attention of later collectors to it, but 
also because so very few hybrids of arctic plants are yet known. 
Plantae sat graciliores quam P. grandiflorae, etiam aliquantulum 
minores quam P. minorts specimina ejusdem loci. Folia tenues, non 
nitescentia, late ovato-elliptica, folia P. minorts similantia. Corolla 
major quam P. minorts, minor quam P. grandifolia sieut utriusque 
rosaceo-albida. Petala late ovata. Stylus rectus, germine subduplo longior, 
superne dilatatus. Stigma quinquelobatum. 
Most of the above named characters do certainly agree with those 
of P. media, this species being, however, a tall plant of the woods in 
Jurope, not occurring in Greenland. A hybrid between P. rotundifolia 
and P. minor has been observed in northern Fennia by KiHi~Mman. 
XXXIII. Rhodoraceae. 
Ledum. 
The History of the interpretation of the Greenland 
Ledum-forms (By M. P. P.). 
Linnaeus in his “Species plantarum”, 1753 labelled a shrub, com- 
mon in wooded bogs in Sweden, Ledum palustre, before his nomen- 
clature often called Rosmarinus sylvestris. The plant was well-known 
to the Swedish people for its fragrance and it was used as a substitute 
for hops in brewing or as an insecticide. The name given by Linnaets, 
has been in later literature applied to the same plant from other parts 
of Europe, and C. Frus Rorrsoiyt determined in 1766 the Ledum sent 
to him from Greenland as L. palustre L. (Act. Hafn. X. 1770. p. 441). 
Although Rorrsott’s plants do not exist, we may infer from the collec- 
tors mentioned by him, that the plants in question belonged to the nar- 
row leaved form (L. decumbens). 
At the same time another Ledum was brought to Europe by several 
travellers from Greenland, Labrador, New Foundland and various parts 
af Canada. It was cultivated in most of the leading botanical gardens, 
and it became soon generally known under its trivial name “Labrador 
tea’ or under the gardener’s name “Ledum latifolium”, being from 
the first what we now call a nomen nudum. The first valid description 
