ANGIOSPERMS. 



All 



bud before tlie opening of the flower shows, especially in Hypericum calydnu?n, the 

 numerous filaments which spring from one original protuberance densely crowded 

 into one bundle. In this and many similar cases the common primordial basal 

 portion of the stamen remains very short, while the secondary filaments lengthen 

 considerably and subsequently present the appearance of a tuft springing from the 

 receptacle, the true nature of which can only be ascertained by the history of its 

 development. If, on the contrary, the primordial basal portion lengthens, as 

 in Calothamnus, the whole stamen is easily recognised as branched even in the 

 mature condition. 



Of no less importance for understanding the entire plan of structure of a 

 flower, and especially the relations of number and position which actually occur, 

 is the cohesion of stamens which grow side by side in a whorl. In Cucurbita, 

 for example, there are, in the earliest stage, five stamens, but at a later period only 

 three are found, two of which are, however, broader than the third ; these are each 

 the result of the lateral coalescence of two stamens. In this case the filaments 



Fig. 337.— Dcvelnpinent of the andrceciuin of Cucurbita Pepo (after Payer); in all the fiiriires the simple stamen is to the 

 riiflit, behind and to the left two double ones. The anthers grow vigorously in length and form verniiforni coils. 



become combined into a central column, on which (as is shown in Fig. 337, ///) the 

 pollen-sacs grow more rapidly in length than the filaments, forming vermiform coils. 

 The relationships are much more complicated and more difficult to understand 

 when cohesion and branching of the stamens occur simultaneously, as in Mal- 

 vaceae. In Althcca rosea, for instance, the filaments form a membranous closed 

 tube which completely envelopes the gynaeceum ; springing from this tube are five 

 verdcal and parallel double rows of long filaments, each of which (Fig. 338, B) 

 again splits into two arms (/), and each of these arms bears a single anther-lobe. 

 The history of development and a comparison with allied forms shows that the tube 

 is formed by the lateral coalescence of five stamens ; but the coherent margins produce 

 double rows of lateral ramifications, in other words, of filaments, which then again 

 split into two arms. A horizontal section of the young staminal tube (Fig. 338, A) 

 shows plainly these double rows of split filaments ; the part [v) which lies between 

 two of these must be considered as the substance of a stamen, the margins of which 

 each bear right and left a simple row of filaments as lacinioe or branches \ In 



^ The strangeness of this conception will disappear if the structure is recalled of a unilocular 

 ovary with numerous carpels coherent at the margins, e.g. Viola, where the ovules arise in double 

 rows on the lines of junction (the placenta). What takes place in one case in the mside m refer- 

 ence to the ovules takes place in the other case on the outside in the formation of the filaments. 



