46 THE AMERICAN BOTANIST. 



single carpel with one parietal placenta, but as it goes on to- 

 ward maturity it begins to put on its disguises. In our most 

 familiar examples, such as are supplied by the bean and pea, it 

 opens as two flat valves. Often the opening is a mere matter 

 of falling apart, but in some of the Cassias the pod is often 

 under considerable tension through drying and when it does 

 open, it does so with a snap that sends the seeds in all direc- 

 tions. On the other hand, many pods like those of the peanut 

 never open while still others open only along one side and 

 therefore conform to the definition of a follicle. We usually 

 assume that the pod is one-celled, but in many of those that 

 do not open there are cross-partitions between the seeds, 

 making a several-celled pod. Proceeding on this line, several 

 species, like the tick-trefoils, have worked out a system of 

 seed distribution by the pod breaking into pieces and thus while 

 the pod cannot truly be said to open, its behavior results ex- 

 actly as if it did. In some of these indehiscent pods, the seeds 

 are surrounded by a juicy pulp as in the tamarind, while in 

 other styles the seeds are found in inflated bladdery pods, as 

 in Colutca. Normally the pods are long and straight but in 

 several species of the genus Mcdicago, to which the alfalfa 

 belongs, the pods are coiled spirally like a snail-shell. The 

 normal pod, as has been said is one-celled, but in addition to 

 species in which there are cross-partitions, there are others in 

 which a projection from the walls of the pod nearly divide it 

 into two longitudinal sections as in the well-known cress fam- 

 ily. In still other plants the pod bears but a single seed and 

 does not open, thus forming ? fruit that in other groups 

 would be called an achene, while in PIcrocarpus, the single 

 seed is winged all around and is thus a samara. In a few 

 species the seeds are covered with a fleshy material forming 

 what is essentially a drupe. 



