THE ADULT SPOROPHYTE 99 



ANATOMY OF CHEIROGLOSSA. 



Material was lacking for a study of the anatomy of the rhizome in 0. palmatum 

 (fig- 7°)' but the structure of the petiole is very much like that of O. pendulum and 

 probably the same relation of the leaf bundles to the bundles of the rhizome obtain 

 as in O. pendulum. The difference in the venation has already been pointed out 

 and the leaves differ also from those of O. pendulum in the fact that stomata are 

 developed only upon the lower side. A feature of this species is the presence at the 

 base of the leaves of very conspicuous multicellular branching hairs, quite different 

 from those found in any other species of Ophioglossum (fig. 70, C). I find that the 

 cells are much more elongated in my specimens than those figured in the account 

 of the Ophioglossaceae given in the Natiirliche Pflanzenfamilien.* 



THE SPOROPHYTE OF BOTRYCHIUM. 



There is much the same uncertainty as to the number of species of Botrychtum 

 that there is m Ophioglossum. Some of the species are exceedingly variable and 

 their limits are difficult to determine. Bitter, in his account of the Ophioglossaceae 

 in Engler and Prantl's "Natiirliche Pflanzenfamilien," states that there are sixteen 

 species. Underwood (Underwood 1) says "about thirty," of which fifteen occur in 

 the United States. Christensen in his Index Filicum recognizes thirty-four species. 



Many of the species are very widespread, being most abundant in the North 

 Temperate Zone. According to Christ (Christ 1), B. lunaria is not only widespread 

 throughout the colder parts of the Northern Hemisphere, but occurs again in the 

 corresponding regions of the Southern Hemisphere, having been reported from Pat- 

 agonia, southern Australia, Tasmania, and New Zealand. A few species occur in 

 the mountain regions of the tropics; thus B. lanuginosum is not uncommon in the 

 highlands of Ceylon, where I collected it at an altitude of about 7,000 feet. 



The simplest member of the genus is Botrychtum simplex, a very variable 

 species occurring at various places in North America, northern Asia, and Europe. 

 Its smaller forms closely resemble a small Ophioglossum (fig. 72, A, B), except that 

 the sporangia are more distinct. From this primitive type, obviously not very 

 remote from Ophioglossum, there is an interesting series of forms leading up to the 

 large species like B. virginianum and B. silaifolium. This latter species, which 

 grows in the mountains of western North America, is perhaps the largest of the 

 genus (plate 7). The plant is sometimes 2 feet high, the leaf nearly a foot in width, 

 and the very large panicle of sporangia 6 inches or more in length. 



In the evolution of the leaf in Botrychium, the sporangiophore shows a devel- 

 opment parallel with that of the sterile leaf. In the forms of B. simplex, having 

 an entirely undivided sterile lamina, the sporangiophore has the form of a simple 

 spike with a single row of large sessile sporangia on either side (fig. 72, A) and very 

 closely resembles a small Ophioglossum. As the sterile leaf segment becomes more 

 and more dissected, there is a corresponding branching of the sporangiophore which, 



* Professor Bower, at the last meeting of the British Association for the Advancement of Science, read a paper on the Anatomy 

 of Ophioglossum palmatum. This has not yet been published, but Professor Bower has kindly furnished me with an abstract of 

 his paper from which the following extract is quoted. 



"It was thought probable that 0. palmatum (the only species of section Cheiroglossa') would share with the species 

 named (/. e., the species of Ophioderma) the character of a divided (leaf)trace, and material collected in Jamaica has shown 

 that it does. The axis is much distended by parenchymatous storage tissue in pith and cortex, and as a consequence the 

 meshes of the stele are transversely widened. From their margins right and left, but not quite simultaneously, arise two 

 strap-shaped strands, which are thus widely apart in their origin. After subdivision into numerous smaller strands, these 

 range themselves into two fan-like semicircles, which spread till their margins meet, forming the circle of strands of the 

 petiole. A remarkable feature of the stock is the intrusion of roots into the bulky pith; this is especially obvious 

 towards the base, where they pass out as thick mycorrhizic roots." 

 This behavior of the roots recalls that of the Marattiaceae, 



