Ampkicarpcea monoica. 337 



allowed to stand. For the present, laying aside the winter 

 type, Ampkicarpcea monoica presents in nature, three dis- 

 tinct kinds of legume. A striking series of transitions is 

 readily made from the purple to the terrestrial, including 

 those tiny flat forms which are not successful in reaching a 

 suitable maturing place. If again we place the winter-type 

 in our list, the series is unusually complete. 



With the purple, and green aerial, the fruit is green, turn- 

 ing brown when ripe, the style persisting and forming a 

 characteristic feature in each, as does also the region just 

 toward the apex. In the winter type, the same remarks as 

 to color change will apply; usually the style disappears; if 

 it remains, it either stands out at right angles to the legume, 

 or it is appressed to the ventral suture. 



The terrestrial form is white, but is soon tinged with 

 pink purple. When ripe, the style has disappeared, the 

 sutures are often scarcely discernible, the color is purple of 

 varying vividness and density. 



Appropriating a word used — possibly introduced — by 

 Huth, 17 , we may properly class Amphicarpaa monoica among 

 heterocarpic plants. In his paper, however, he places it 

 among amphicarpic forms. 



The histological structure of purple, green aerial and 

 winter-type legumes is similar. Numerous stomata alike 

 in size and shape are found; these are surrounded by several 

 subsidiary cells. The epidermal cells are irregularly isodi- 

 ametric. (Plate XXXIV., Fig. I.) Just beneath the epi- 

 dermis, lie one or sometimes more layers of sclerenchymatous 

 fibres, closely arranged, tapering so that they fit together to 

 form a mechanical device for producing the inflation of the 

 pod. In transverse section, in addition to what has been 

 mentioned, we find cells resembling mesophyll and con- 

 taining chlorophyll. The inner epidermis is thin, and has 

 no stomata. The glistening, somewhat opaque appearance 

 of the interior of the legume is probably due to air spaces 

 under the epidermis. The mesophyll tissue in the winter 

 type appears of looser texture than the others. 



