Notes on the anatomy of Sesban macrocarpa Muhl. 



* 



Maud J. Staber 



(with plate 34) 



Sesban macrocarpa was first described by Muhlenberg in 1818; 

 later, Pursh changed the generic name to Sesbania, which form is 

 used by some authors. The species under consideration is the 

 only representative of the genus known in North America, although 

 there are a number in other parts of the world in warm or tropical 

 regions. Sesban macrocarpa is one of the annuals which flourish 

 under the conditions that exist in Arizona and the southwest in 

 general, and further south to Central America, although It is known 

 in the eastern section as far north as Pennsylvania. It is placed 

 in the Papilionaceae near Robinia, Astragalus^ etc., in the tribe 

 Galegeae. 



Before going into details of the anatomical structure of the 

 plant in question the following review of the anatomical features 

 common to the Papilionaceae will be of interest. The character- 

 istics common to these forms are : f (l) ducts with simple open- 

 ings, (2) simple pitted wood-prosenchyma, (3) lack of. crystal 

 glands, and (4) scarcity of the usual one-celled hairs, (5) ducts 

 filled with brown albuminous substance, (6) hairs which usually 

 consist of one row of cells having one or more short basal cells 

 and one long end-cell, besides (7) excretion of calcium oxalate in 

 the form of staff-like crystals. As the other characteristics are 

 not common to all species, they will not be considered here. 



The material used was chiefly raised from seed at the New 

 York Botanical Garden. That from which most of the work was 

 done was fully mature, having flowered. The plants all averaged 

 about the same height, the particular one studied being 105 cm. in 

 length. In order to facilitate orienting the sections, the plant was 

 cut into seven lengths, successively shorter, and the parts were 



* BriUon, Manual of the flora of the Northern States and Canada, 550, 

 tSolereder, Anatomie der Dicotyledonen, 288. 



625 



