585 



Dehiscence of the Capsule. 

 In Mem. i, 23, Naudin (1883) includes the classification (this Part, p. 573) : — 

 (a) Species with exsert capsules. 

 (&) Species with enclosed capsides. 



To use his words, a group (a) and First Section, " Capsule more or less exsert, 

 that is to say, notably exceeding the calyx-tube " ; and a group (b) and Second Section, 

 '' where the tips of the capsule valves are either sunk or hardly attain the margin of 

 the calyx-tube," it is, of course, understood that the lines of demarcation are not 

 sharp. He has other groups based on the valves. 



At an extraordinary meeting of the Societe Botanique de France held in Algiers 

 in April, 1892, Professor L. Trabut read a paper (p. xli), " Sur la dehiscence des Capsules 

 dans le genre Eucalyptus," of which the following is a translation : — 



There are fine collections of Eucalypts in Algiers, the most interesting, without doubt, being that 

 of M. Cordier, established in 1863. For more than fifteen years M. Cordier planted in Ms different 

 properties more than 2,000 to 3,000 Eucalyptus trees each year, and at the present time, at Maison-Carree 

 in the domain of El-Alia, more than 5,000 trees have grown into fine specimens, representing more than 

 100 species or varieties. 



It was in seeking to utilise these precious materials with the view of finding indications as to the 

 best species to propagate that I have been verifying the determinations, and have been noting certain 

 peculiarities which appear to me to be worthy of interest. The variations in the mode of dehiscence of the 

 capsule may perhaps be taken into consideration, and furnish some useful characters to complete the 

 descriptions which one does not take too rigorously in a genus of allied and polymorphic species. 



We know that the capsule in Eucalyptus is not entirely free, but adnate to the calyx-tube, resulting 

 from the concrescence of external verticels, the summit alone of the capsule remaining free. This summit 

 sometimes projects outside the calyx-tube, and sometimes is surmounted by the edges of the calyx-tube: 

 the capsule is then included. At maturity the fruit opens by slits on a level with the dorsal vein of the 

 part remaining free of the carpels ; this is a loculicidal dehiscence ; but this loculicidal dehiscence is not 

 as uniform as one might think, and its variations can be classified in the following way : — 



(a) The capsule opens by 3-5 loculicidal slits ; but the summits of the valves remain united at the 

 centre of the stylic column (style), of which the base is more or less persistent. The slits open at the 

 maturity of the capsule on the plant ; but the seeds do not fall out except after a half-opening, which 

 produces the desiccation of the capsule (figs. 1 and 2. to be reproduced later, J.H.M.). 



(b) The capsule opens by 3-5 loculicidal slits ; the very thick valves converge towards the centre, 

 remaining adherent to the partition so well that the whole of the slits form a star. The mass of the piled 

 up seeds has the appearance of a projecting cushion with a hole in the middle, after the fashion of a star, 

 and the seeds, obstructing the slits of the capsule, may remain in that state for years; but, when the 

 capsule dries, which rapidly happens when it is separated from the tree, the seeds fall out because of the 

 contraction of the valves and of the membrane surrounding the cavity of the ovary (fig. 3, to be reproduced 

 later, J.H.M.). 



(c) The valves, more or less membranous, deltoid or linear, converge at the beginning towards the 

 centre, then, becoming free, they rearrange themselves, leaving the cells largely open (fig. 4, to be reproduced 

 later). These valves may be also deeply inserted in the calyx-tube. 



(d) The valves, neatly arranged on'the summit of the capsule, lose their tops by decay and drying, 

 and assume the form of a triangular fragment. These apices of the valves remain for a greater or shorter 

 period in their place; after their fall, the seeds which appear are retained by the bases of the valves 

 remaining in a living state. The central opening in obliterated by piled-up seeds ; then the seeds escape 

 by the contraction of the base of the valves, and the desiccation of the capsule. The whole of the valves 

 can also dry off and fall in the shape of an operculum; the valves are also partly or wholly deciduous in a 

 large number of species (fig. 5, to be reproduced later). 



