THE EUSPORANGIATE FERNS AND THE STELAR THEORY 
D. H. Campbell 
(Received for publication January 17, 192 1) 
Some thirty years ago, as the result of an extensive series of investi- 
gations, Van Tieghem, the distinguished French botanist, brought forward 
his stelar theory which offered an interpretation of the nature of the tissue 
systems of the higher plants quite different from that which had been held 
by Sachs, de Bary, and other earlier investigators. 
Van Tieghem 's views, with some more or less important modifications, 
have been pretty generally accepted by the morphologists of the past two 
decades, and have been assumed to apply to all the vascular plants. 
Among the forms which have been the subjects of frequent and detailed 
study in regard to the nature of their stelar structures are various ferns. 
These studies have been directed largely toward the elucidation of the evo- 
lution of the stelar structures of the Filicineae and have included a study of 
many fossil ferns as well as the existing types. These investigations have 
thrown much light upon the relationships existing between the many Palaeo- 
zoic fern-like plants and their living relatives. 
An extensive literature on the subject has grown up in the past twenty 
years, especially in England, and with it a somewhat elaborate terminology 
based upon the assumption that the fibro-vascular skeleton of the fern stem 
is a strictly cauline "stele" with which the corresponding foliar bundles 
are simply connected by the so-called ''leaf-traces." 
The general acceptance of Van Tieghem's stelar hypothesis and its 
modification by Strasburger and other investigators, especially in England, 
are sufficiently familiar to students of plant anatomy. Van Tieghem con- 
cerned himself chiefly with the Spermatophytes, and his interpretation of 
the stelar structures of the ferns has been a good deal modified by the 
English investigators and by Jeffrey in this country. The latter^ has 
summarized these conclusions, and this has also been done at length by 
Bower^ and Schoute.^ 
Some of the most recent contributions to the subject^ apparently accept 
these views as applying universally to the ferns, and quite ignore the 
evidence brought forward by the writer nearly ten years ago,^ and amply 
^ Jeffrey, E. C. The structure and development of the stem in Pteridophyta and 
Gymnosperms. Philos. Trans. Roy. Soc. B, 195: 119-146. 1902. 
2 Bower, F. O. The origin of a land flora. London, 1908. 
^ Schoute, J. C. Die Stelar-Theorie. Jena, 1903. 
^ E.g., Thompson, J. M. New stelar facts, and their bearing on stelar theories for the 
ferns. Trans. Roy. Soc. Edinburgh 52: part 14, no. 28. 1920. 
^ The Eusporangiatae. Carnegie Inst. Washington Pub. 140. 191 1. 
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