The Comparative Structure of the Flowers in. 
Polygala polygama and P. pauciflora, 
with a Review of Cleistogamy. 
(WITH PLATES XVI-XVII.) 
By CuarLes Hucu SuHaw, Pu. D., 
Professor of Botany in Temple College. 
[Submitted to the University of Pennsylvania in Partial Fulfillment of the Requirements for- 
the Degree of Doctor of Philosophy.] 
In the genus Polygala only two species, so far as known, 
exhibit cleistogamy. Both are natives of the Eastern United 
States. One is P. polygama, often abundant along our sandy 
coasts, the other is P. paucifolia, the beautiful so-called 
Flowering Wintergreen of more interior districts. 
The former, alike from the abundance of the cleistogamic 
flowers it produces, and the presence of intermediate types 
now for the first time described, has been the chief subject of 
the present study and will be first dealt with. 
The detailed description of the various types of flower may 
best be prefaced by recapitulating what is known of the 
flowers of the genus. 
Conspicuous blooms are borne by all members of the 
genus. These are generally in racemose clusters, and are 
sometimes very showy. The typical aérial flower is very 
irregular. In the calyx the two lateral, interior sepals are 
greatly developed as petaloid wings. The corolla consists 
of three petals, one anterior and two posterior, the two lateral 
of the theoretical five being suppressed. Of the three the 
anterior one is greatly developed as a hood covering the 
stamens and pistil. The stamens are eight in number, 
the anterior and posterior ones of the theoretical ten being 
wanting. They are monadelphous, being united below, and 
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