388 BOTANICAL GAZETTE - [DECEMBER 
genera mentioned in the preceding. By Foxwortuy™ a general 
discussion of discoid pith has been presented. Finallyby the writer™ 
the structure of the pith in Phytolacca decandra L. has been described 
and figured 
While the discoid pith is thus characteristic of the species of 
certain genera, it has been shown that in Begonia, Forsythia, 
Jasminum, and Phytolacca this structure occurs only in certain 
species. Juglans and Pterocarya are definitely separated from 
the other genera by the possession of a discoid pith. It is a very 
interesting structure, which, however, must not be confounded 
with cases where the pith is solid, and divided by horizontal dia- 
phragms of sclerotic cells, so characteristic of many Magnoliaceae, 
Anonaceae, Ternstroemiaceae, and Convolvulaceae. 
Ciinton, Mp. 
EXPLANATION OF PLATES XV, XVI 
PLATE XV 
Carya alba 
Figs. 2, 3, 4, 7, 8, 10, 11, 13, and 14 are enlarged. 
Fic. 1.—Staminate flower: St, stem; L, bract; P, prophylla; 5S, stamens. 
Fic. 2.—Involucre of staminate flower, seen from outside. 
Fic. 3.—Staminate flower, side view. 
Fic. 4.—Stamen 
Fic. 5.—Pistillate flower: PL, perianth leaves; other letters as preceding. 
Fic. 6.—Pistillate flower with single perianth leaf. 
Fic. 7.—Pistillate flower, side view; PS, petiole. 
Fic. 8.—Pistillate flower, seen from above. 
Fic. 9.—Cross-section of inner part of primary root of seedling in second 
year: St, stereome strands outside secondary Jeptome (L); Camb, cambium; 
H, hadrome; PR, parenchymatic ray; P, pith; x 320. 
Juglans nigra 
Fic. 10.—Staminate flower, seen from outside; stamens removed. 
Fic. 11.—Two stamens, side and front view. 
Fic. 12.—Branch with pistillate flowers; natural size 
Fic. 13.—Longitudinal section of pistillate flower; P+, perianth leaves. 
Fic. 14.—Cross-section of stigma. 
3 Foxwortuy, E. W., Discoid pith in woody plants. Proc. Indiana Acad. Sci. 
P. I9I. 1903. 
™ Horm, THEO., Medicinal plants of North America. 9. Phytolacca decandra 
L. Merck’s Report. p. 312. 1907 
