16 ILLINOIS BIOLOGICAL MONOGRAPHS [106 



the various species. The different forms are fairly constant, and, within 

 certain limits, offer good differential characters. 



Their function is somewhat doubtful. Knuth says (1899): "In den 

 weisslichen oder rotlichen, meist funf-, aber auch vier-, drei- und zweiza- 

 ligen Bliiten wird der Honig durch fiinf und weniger sich liber dem Frucht- 

 knoten zusammenbiegende Schuppen gegen Regen geschiitzt." Whether 

 they serve any function other than this one of protection is rather doubtful. 



The stamens are inserted at the top of the corolla tube. In some 

 species (C. exaltata, C. coryli, etc.) the union of the filament to the tube 

 below its separation is more or less evident, but in most of them it is not 

 readily noticeable. The anthers range in shape from oblong-linear to 

 orbicular, the shape being fairly characteristic for each species. They are 

 introrse, adnate or more or less versatile, and open longitudinally. The 

 pollen sacs are more or less divergent at their base in some species giving 

 the anthers a sagittate appearance. In C. polygonorum and C. glandu- 

 losa the pollen sacs are frequently widely separated by a connective that 

 reaches to the apex of the anther. This connective has been found some- 

 what prolonged into a slight apiculation in some specimens of C. americana 

 and others. The filaments are slender or subulate, and somewhat oval in 

 cross section. Their length shows a rather wide range. In some the 

 anthers are quite sessile while in at least one species (C. gracillima) they 

 are on filaments that are longer than the corolla lobes. This length of 

 the filaments, however, is variable within certain limits for members of 

 the same species. 



The two-celled, four-ovuled ovary is ordinarily very small but even in 

 the younger flowers gives an indication of the shape of the capsule-to-be. 

 The ovules are basal, anatropous and provided with one integument. The 

 styles are of different lengths and shapes for the different species. They 

 are for the majority of the species as long as or longer than the ovary. In 

 most of the species they are slender and of the same thickness throughout, 

 but a number, chiefly Mexican, possess styles having a greater diameter 

 at the base and tapering towards the stigma. The common position for 

 the styles is upright, but in some species (C. coryli, C. polygonorum, C. 

 mitraeformis, etc.) they become widely divergent as the fruit matures. In 

 the group Monogyna the styles are united more or less completely; in the 

 others they are entirely separated. The only representative of the 

 Monogyna section found in this country so far is C. exaltata. Its styles, 

 while more or less connate, are easily separable and show a distinct line of 

 cleavage, indicating that the union is incomplete. 



Two distinct types of stigmas are found. The North American forms 

 all possess the semi-globular capitate type which characterizes the group 

 Grammica, with the exception of C. exaltata which has the capitate type 



