80 



Rhodora 



April 



(where it meets the lobule) it is usually not dilated at all and may 

 even he slightly deeurrent, the keel being often obsolete. The small 

 and narrow lobules, rounded or very bluntly pointed at the apex, arc 

 attached by a line which is straight or only slightly arched, and tin- 

 inner edge is usually shorter than the outer, an unusual condition in 

 the genus Porella. The leaf-cells average about 20 ft in the middle of 



FigS. 1-13. PORELLA PINNATA L. 



1. Hrunch (of first order) bearing a female brunch with a perianth, and also a sterile hnineh, 

 ventral view. X 15. 2-4. Hracta and bractoole from a single involucre, X 35. S. A bract 

 from another involucre, X 35. 6-8. Bracts and bructeole from a third involucre, X 35 

 9-11. Bracts and bracteole from a fourth involucre, X 35. 12. Cells from the base of a 

 bract (lobe), showing papillae, X 200. 13. Teeth from the mouth of an immature perianth, 

 X 200. Figs. 15 were drawn from a specimen collected at Columbus. Kentucky, by N. L. T. 

 Nelson 1 ',H7; Figs. C-8, 12, 13 from a specimen collected at Cranby, Connecticut, by C. K. 

 Nichols; Kigs. '.Ill, from I he type specimen of Mtuliilhrrn inirrorhynrhii in the Taylor herbarium. 



the lobe and show small but distinct trigones. In the indexed por- 

 tion the marginal cells extend at right angles to the edge and form a 

 distinct border. The underleaves (Fig. 1) are slightly if at all de- 

 current, the line of attachment (as in the case of the lobules) being 

 straight or only slightly arched. 



