'Amphicarpcra monoica. 325 



Aerial Cleistogamous Flowers. 



Not until the former blooms are fairly well developed is 

 this variety seen. They appear in the axils of cauline 

 leaves, lower down than the purple, and also upon numer- 

 ous axillary shoots. Frequently they are solitary ; sometimes 

 they are found in a short, closely clustered few-flowered 

 rudimentary raceme. Occasionally one or two flowers 

 develop at the base of the purple raceme. Again they 

 are found upon a long shoot resembling that upon which 

 the subterranean pods develop — that is, we see a slender 

 axillary branch upon which at intervals, occur solitary 

 legumes, often to the number of three or four. This 

 special shoot frequently branches and occasionally appears 

 to terminate in the production of two pods growing from 

 opposite sides of the apex. The last described structures 

 will be discussed in connection with the underground type 

 of legume. 



When once recognized, the two varieties of aerial flower 

 need never be confused, either in flower or fruit. 



The calyx is four-parted, as in the preceding, but is 

 smaller and the teeth are not so pointed nor so long. It is 

 pubescent, but the color is always greenish white. 



Even the tiny bud, an eighth of an inch in length, pos- 

 sesses a flattened appearance quite different from that of the 

 purple one. 



Upon dissection a comparatively large ovary is seen, 

 bearing recurved style, whose stigma is not usually capi- 

 tate. This ovary is nearly sessile, and is somewhat hairy, 

 particularly upon both anterior and posterior margins. 



Occasionally a rudimentary vexillum is present, but 

 practically the flower is apetalous. 



The stamms are typically ten, and show a small filament- 

 tube, or they may be distinct. They are quite small and all 

 transitions of perfection in the anthers exist. Plate XXIX, 

 Fig. 1, shows the pistil surrounded by the anthers, vary- 

 ing in the degree of perfection indicated. In Fig. 2, a 



