fc>"*"fc> 



it appears that in the Osmundace<t there may be very con- 

 siderable variations in the structure of the root-tip, and that 

 of our native species, O. Claytoniana, on the whole, departs 

 least from the ordinary fern-type, and may be looked upon 

 as the most nearly related to the true Leptosporangiatae. 2 



Of the two species of Botrychium, B. Virginianum approaches 

 more nearly the Filices in the structure of its roots, as it does 

 in other respects." A further investigation of Ophioglossum 

 and the simpler species of Botrychium will probably show in 

 these a still further departure from the type than in B. 

 ternatum. 



Bloomington, Indiana, November, 1890. 



Explanation of Plate V. 



all 



All magnified about 175 diameters, x, apical cell, a, a, the primary w 

 in the young segment. The boundaries of the younger segments are indicated by 



tne nenvv inp<; ° 



the heavy lines. 



Figs. 1-3. Osmunda cinnamomea. Fig. 1, longitudinal; 2 and 3, trans- 

 verse sections, tr, young tracheae. 



FifT; ! 1 ° C,a y toniana - *" 5. longitudinal; 6, 7, transverse sections. 

 Jjig. 8 is a transverse section a short distance below the apical cell In fig. 5 

 the youngest seg ment (x'), closely resembles in form the true initial I cell (.<) 



1 Y an T K he ? and P°o«°t, dispute the view that the epidermis of the root in 

 any ferns is derived from the lateral segments at all, but claim that t originates 

 from the outer segments, the same that f, ,rm the root-cap 



st ndv 'of SfSS n .H giWn J er f based u ? on the roots, is also confirmed by a 

 rtudj < t the protha hum which in several respects resembles the Polvnodiace* 

 mor- cl K than does either O cinnamomea or O regalis ™> poaiace* 



« Campbell: On the affinities of the Filicinese; Bet. Gatette, Jan., 1890, p. 5 





42 The Botanical Gazette. [February, 



plerome initial cell becomes separated before the division of 

 the outer cells of the segment and the initials of the periblem 

 and dermatogen. 1 The cap segments, however, show much 

 less regularity, and the stratification of the root-cap is soon 

 entirely lost. Comparing, too, the apex of the root (exclu- 

 sive of the root-cap) with that of most other ferns, it is 

 found to be much more convex. 



Botrychium Virginianum. — Comparing the root of B. 

 Virginianum (fig. 11) with B. ternatum, while the structure 

 on the whole is closely similar, the former species approaches 

 more nearly the fern-type. Sometimes (fig. 12) the cross- 

 section shows almost as perfect regularity as in the Polypod- 

 iacea.\ and this is evident, too, though to a less degree, in 

 longitudinal sections. The root-tip is flatter than in B. 

 ternatum, and the stratification of the root-cap more evident, 

 although much less so than in the Filices. 



CONCLUSIONS. — As a result of the foregoing; statements, 





