The Gametophyte and Embryo of Botrychium 
obliquum, Miihl. 
BY 
DOUGLAS HOUGHTON CAMPBELL, 
Stanford University , California. 
With Plate VIII and eleven Figures in the Text 
HE genus Botrychium comprises about thirty-five species, 1 of which 
X about half occur in the United States. Most of the species are found 
in temperate regions, the few that occur within the tropics inhabiting the 
cooler mountain districts. 
Our knowledge of the gametophyte and embryo is based mainly upon 
a study of two species, B. Lunar ia , (L.) Sw., 2 and B. virginianum , (L.) Sw. 3 
In 1905 Lyon 4 published a brief account of the embryo of B. obliquum , 
Miihl., which was found to differ so much from the other species that he 
proposed to separate it as the type of a new genus, Sceptridium. 
Dr. Lyon has very generously turned over to the writer his collection 
of gametophytes of B. obliquum , and also a large series of sections which he 
had made, as well as a number of photographs. From Dr. Lyon’s sections, 
supplemented by sections made by the writer, a fairly complete study was 
made of the development of the reproductive organs and embryo, and it 
was thus possible to examine in detail the differences between B. obliquum 
and the two other species whose development was known. 
The Gametophyte. 
The structure of the gametophyte of B. obliquum is much like that of 
the other species that have been investigated. The gametophyte is a 
subterranean, tuberous body, somewhat flattened horizontally and having 
a median, longitudinal, dorsal ridge upon which the antheridia are produced. 
The mature gametophyte (PI. VIII, Figs. 3,4; Text-fig. 1) is about 3 to 6 mm. 
1 Christensen, C. : Index Filicum, 1906. 
2 Hofmeister : The Higher Cryptogamia. Ray Society, 1862. Bruchmann, H. : Flora, xcvi. 
203, 1906. 
3 Jeffrey, E. C. : Proc. Canad. Instit., 1898. Campbell, D. H. : The Eusporangiatae. Carnegie 
Institution Publication, No. 140, 1911. 
4 Lyon, H. L. : Bot. Gaz., xl. 455, 1905. 
[Annals of Botany, Vol. XXXV. No. CXXXVI 1 I. April, 1921.] 
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