260 MR. A. S. HORNE — A CONTRIBUTION TO 



o 



Tjecome entirely obsolete. It is clear that the terminal ovules of the Caprifoliacese have 

 not all originated in the same manner, but they are either axially situated or of axial 



n, whereas those of the Hamamelidacese and of Araliaj Acanthojpanaa;, and Hedera 



are situated parietally. 



7. The vascular structure of tlie single axially-suspended ovule in the genera with 



uniovulate loculi is similar to that of a pair of ovules in the pluriovulate loculi — two 

 bundles enter the ovule and join to form one in the raphe. But in Aralia^ AcanthOjpmiax^ 

 and Hedera, and in the Hamamelidacese, where the terminal fertile ovule is parietally 

 suspended, only a single bundle enters the ovule. 



8. It is evident that the ovaries of several genera of Caprifoliacese have reached their 

 present stage of construction in different ways, and in all probability from more than 

 one prototype. Leycesteria and Diervilla present strong resemblances — both genera 

 possess a tubular corolla with an irregular limb, the loculi of the ovary are in each case 

 pluriovulate and the fruit polyspermous — nevertheless, the ovaries are structurally 



1 



different. In Diervilla the placentae are adpressed throughout the greater portion of 

 the ovary ; in Leycesteria they are congenitally united in the lower portion. Now, 

 according to published descriptions, ovaries of both the above-mentioned types occur in 

 the flower of the species of the Hamamelid, Mhodoleia, Hence it is not improbable that 

 the structures obtaining in Diervilla and Leycesteria originated from prototypic ovaries 

 fluctuating like those of Mhodoleia in the degree of centripetal development of the 

 carpels. But it would be unwise to consider the prototypes necessarily identical, since 

 the loculi in Leycesteria contain biseriate rows of ovules, whereas those of Diervilla may 

 contain multiseriate rows. The latter condition recalls that of Dolyosma, a genus 

 included among the Saxifragacese in Engler*s System. 



The remaining Lonicerese, with the exception of Lonicera itself and Triosteum, 

 possess dimorphic carpels. Abelia and Linncea differ in form and habit, but the ovaries 

 are structurally similar; the same is the case with regard to Symphoricar^pus and 

 Dipelta. The ovaries of SympJioricarpus and T?^iosteum are structurally dissimilar, and 

 must be regarded as having originated independently from an ovary constructed like 

 that of Leycesteria. 



The seriate rudimentary ovules of Viburnum and the biseriate rudiments present 

 in Sambucus indicate that the ovaries in both genera were originally pluriovulate, whilst 

 the structural characteristics of the ovary itself suggest that each has passed through 

 the Leycesteria stage of construction. Nevertheless, the Sambucese have long been 

 recognized as forming a distinct subsection of the Caprifoliaceae, distinguished from the 

 Lonicerese, which possess congenitally united styles and a tubular corolla, by their rotate 

 corolla and free styles. Indeed, Hock established a separate family for Sambucus — the 

 Sambucacese. Moreover, from a study of the ovary in Sambucus and Viburnum, it seems 

 clear that the process of abortion has been in each case a different one and dissimilar to 

 the processes that have aff'ected the construction of the ovary of the Lonicerese. Hence 

 the actual origin of the Sambucese remains obscure, and it is by no means certain 

 whether the descent of either Sambucus or Viburnum could be legitimately traced to 

 prototypic forms of the Lonicereae. 



