ANGIOSPERMS. ^y a^ 



the small flowers of Dipsacacece is of special interest, each being surrounded, within 

 the crowded inflorescence, by a membranous tube, which here forms the epicalyx. 

 Sometimes, after the perianth and sexual organs have begun to be formed, an ele- 

 vation of the flower-stalk, at first annular, is formed below the flower, growing up 

 afterwards in the form of a cup or saucer, and bearing scaly or spiny protuberances. 

 A structure of this kind is called a Cupule ; and the cup in which the acorn of the 

 various species of oak is seated is of this nature ^ In this case the cupule surrounds 

 only one flower, in the sweet-chestnut and beech on the other hand it encloses a 

 small inflorescence. This spiny cupule afterwards splits from above, separating into 

 lobes, to allow the escape of the fruit which has ripened within it. When an 

 inflorescence is surrounded by a peculiarly developed whorl or rosette of leaves, as 

 in Umbelliferce and Compositce, this is called an Involucre ; when a single sheathing 

 leaf envelopes an inflorescence springing from its axis, it is a Spathe. Both involucre 

 and spathe may assume a petaloid structure, the former, for example, in Cornus 

 florida, the latter in Aroidece. 



The Andrcccium is composed of the assemblage of the male sexual organs of a 

 flower. Each separate organ is called a S/ainen, and consists of the Anther and its 

 stalk the Fihvmnt, which is usually filiform, but sometimes expanded like a leaf. 

 The anther consists of two longitudinal halves (anther-lobes) placed on the upper 

 part of the filament right and left of its median line; and the portion of the filament 

 which bears the lobes of the anthers is distinguished as the Connective. 



The lateral position of the stamens on the floral axis (the receptacle) is quite 

 unmislakcable in all hermaphrodite and in most exclusively male flowers. Their 

 lateral position, their exogenous origin from the primary meristem next the ptinctu?n 

 vegetalionis of the floral axis, their acropetal order of development, and the frequent 

 monstrosities in which the stamens assume more or less the nature of petals, or even 

 of foliage-leaves'-, place it beyond doubt that they must be considered morpho- 

 logically as foliar structures, and make it convenient to term them Staminal Leaves ; 

 the filament, together with the connective, being considered as the leaf, of which 

 the two anther-lobes are appendages. From a morphological point of view it is 

 therefore indiff^erent whether the filament (or true leaf) greatly preponderates in size, 

 or is inconsiderable as compared to that of the anther. Only very recently three 

 cases have become known in which the anther appears itself to be a product of the 

 floral axis, and the stalk which corresponds to the filament is the floral axis itself. 

 According to Magnus^, the vegetative cone of the male floral axis of Naias becomes 

 transformed into quadrilocular anthers by the formadon of pollen-mother-cells in 

 four peripheral longitudinal strips of its tissue. Kaufmann had previously described 

 a somewhat similar process in the case of the anther of Casuarina ; and, according 

 to RohrbachS the apex of the floral axis of Typha either itself developes into the 

 anther, or it first of all branches and then forms an anther on each branch. It 

 would carry us too far to give reasons for the doubt already expressed (p. 426), 



' On the development of the acorn-cup see Hofmeister, Allgemeine Morphologie, p. 465. 



2 [On ' phyllody ' and ' petalody ' of stamens see Masters, Vegetable Teratology, Ray Soc. 1869, 

 pp. 253-256, and 285-296. — Ed.] 



3 Magnus, Bot. Zeitg. 1869, p. 771. 



* Rohrbach, in Sitzungsber. der Gesellsch. naturf. Freunde m Berlin, Nov. 16, 1869. 



