4o6 BOTANICAL GAZETTE [may 



ii. Sinnott, E. W., The anatomy of the node as an aid to classification of 

 angiosperms. Amer. Jour. Bot. 1:303-322. pi. 4. 1914. 



12. Sinnott, E. W., and Bailey, I. W., Investigations on the phylogeny of 

 the angiosperms. 3. Nodal anatomy and the morphology of stipules. 

 Amer. Jour. Bot. 1:441-453. pi. 1. 1914. 



EXPLANATION OF PLATES XX, XXI , 



PL A TE XX 



Fig. i. — Section through node showing abscission zone by means of which 

 the leaf is shed; a, only abscission zone present. 



Fig. 2. — Showing continuous abscission zone (a) for stipule and petiole at 



early stage of growth. 



Fig. 3. — Dark line at base of stipule showing point of abscission; note 



that it is distal to attachment of petiole. 



Fig. 4. — Instance of extreme swelling in node below point of abscission 



of leaf ; in such instances scar scale is not shed. 



Fig. 5. — Enlarged view of shedding of scar-scale (a) in Amygdalus David- 

 iana as result of early spring growth ; shedding of this type occurs only when 

 contour of node is relatively flat . 



Figs. 6-9. — Variation in gland position and number; types illustrated 



are 2-0 (2 on petiole and o on leaf base), 1-0, 1-1, and 0-1. 



PLA TE XXI 



Fig. 10. — Leaf of Salix lucida showing glands similar to those of leaf 

 serrations crowded at base. 



Figs. 11-15.— Types of proliferation of petiolar glands into leafy out- 

 growths. 



Fig. 16. — Node of Shepherdia argentea showing shedding of scar scale 

 similar to Amygdalus. 



Fig. 17. — A node of Carnus stolonifera showing same as 16. 



Figs. 18-28. — Bud scales and basal leaves from young shoot of Dye- 

 house cherry, presenting series in separation of stipules from leaf blade. 



Fig. 29.— Enlarged basal leaf illustrating venation of stipules and leaf 

 blade; note that veins of stipules arise as branches of lateral strands. 



Fig. 30. — Petiole showing prominence of lateral bundles in young leaf. 



Fig. 31. — Shedding of dead scar scale in Amygdalus Davidiana from which 

 stipules and petiole abscissed previous season. 



Fig. 32.— Node of young plum stem showing relation of line of abscission 

 in stipule and petiole. 



