NEW PHYTOhOGIST. 
Vol. VI., Nos. 3 & 4 . March & April, 1907. 
LECTURES ON THE EVOLUTION OF THE 
FILICINEAN VASCULAR SYSTEM. 1 
By A. G. Tansley 
(Lecturer on Plant Anatomy at University College, London). 
[Text-Figs. 1—22]. 
II.— The Botryopteride/E. 
The Palaeozoic forms grouped under the family name Botryo¬ 
pterideae are in many respects the most primitive ferns known. 
Their sporangia are intermediate between the eusporangiate and 
the leptosporangiate types, having a considerable resemblance to 
those of the Osmundaceae. Their vascular structure shows a very 
considerable range, but the various types have a good deal in 
common and present suggestive resemblances to some of the 
primitive Cycadofilices, as well as to the Osmundaceae and 
Hymenophyllaceae among recent ferns. Arber is of opinion 2 that 
the Botryopterideae (or rather the larger ill-defined group of 
“ Primofilices ” in which he includes the Botryopterideae) had 
passed the maximum phase of their development in later Palaeozoic 
times when the Cycadofilices were a dominant group, while the 
modern Leptosporangiate Ferns had scarcely emerged as a definite 
phylum. All these considerations point to the probability that the 
Botryopterideae stand near the ancestors of the different phyla of 
fern-like plants. 
In general characters 3 these plants were certainly true ferns in 
the modern sense. In habit they appear to have varied in much 
the same way as the members of a modern leptosporangiate family 
frequently do, some having comparatively short rhizomes with 
closely crowded leaves, others having longer internodes and creeping 
or climbing stems. Of the leaves themselves we do not know a 
1 A Course of Advanced Lectures in Botany given for the 
University of London at University College in the Lent 
Term, 1907. 
2 Arber, ’06. 3 Scott, ’00. 
