40 



Mueller, in the definition of the genus (" Eucalyptographia ") says — ■ 



" . ... discal space intervening between the (inner, J.H.M.) edge of the calyx and the base of 

 the valves from narrow to very broad in different species, and not seldom protruding." 



. . . discal expansion forming a narrow rim beyond the calyx.teeth." (Specific description 

 of E. tetrodonta.) 



" ■ . . discal lining generally much extended beyond the ovary." (Generic definition of 

 Eucalyptus—" Eucalyptographia.") 



The following are synonyms : — 



Discal-lining. 

 Floral disc (flower). 

 Capsular disc (fruit). 



Let us begin with some preliminary observations. 



Disc or Discal-lining. In E. Preissiana, E. megacarpa, E. globulus, and E. alpina, 

 which we take as examples, the thick band or expansion at the top of the fruit is an 

 enlargement of the floral disc. Its development in the fruit or capsule can be traced 

 from the floral stage. In all species examined it varies somewhat, but its presence, as 

 far as I have observed, is indicated by the usually dark zone or lining at the base of 

 and on the sides of the calyx -tube. In the species mentioned, the pulvinate gland-like 

 processes are present on the floral disc, and 1 as the ovary develops, so also does the 

 disc. As the ovary develops, it grows upwards and outwards, and apparently more so 

 in the centre, until it is carried, with the 'disc, beyond the level of the calycine rim. 

 The rim then increases in thickness, and at the same time gradually extends over the 

 valves of the capsule, but in all cases leaves the tips of the valves free. In E. Preissiana 

 the disc is entirely free from the valves, and forms a thick crenate layer above them on 

 the inner margin, while the outer edge is fused to the calycine portion of the capsule. 

 The disc therefore derives its nutriment from the calycine portion, and not from any 

 portion of the valves or ovary. 



The term " discal-lining " applied by Mueller to some species is a very appro- 

 priate one, for in the species mentioned the calyx-tube cup is deep, and has a dark 

 carnose lining which extends towards the ovary in a wave or crenate line, and is 

 differentiated from the ovary by the colour, that of the latter organ being always much 

 paler. The discal lining is naturally more noticeable in species with large flowers and 

 fruits. The term could be conveniently used in descriptions when the disc is obscure, 

 because it is, like the disc, an important character, as it is very largely responsible for 

 the morphosis of the fruit. 



