122 



Dimorphism in Two South Australian 

 Cruciferous Plants. 



By Professor Balph Tate. 

 [Read October 4, 1898.] 



Bentham, in Fl. Austral., I., p. 80, thinks it possible that 

 Oeococcus pusillus (a monobypic genus) " may be a dimorphic 

 state of a species of another genus ... a radical-leaved 

 Blennodia, for example." 



GeocoGCus pusillus is recorded by F. von Mueller in " Census 

 Australian Plants," 1882, for W.A., S.A., V., and N.S.W.; and 

 Queensland is added in the second supplement to that census 

 published in 1885. For South Australia the species has occurred 

 at the following localities on the authority of Baron F. v. 

 Mueller : — River Murray (in litferis to the writer). Fowler Bay 

 (Mrs. Richards, in Trans. Roy. Soc, S. Aust., vol. III., p. 172, 

 1880), and Ardrossan, Yorke Peninsula {J. G. 0. Tepper, T.R.S., 

 S. Aust., voL III., p. 175, 1880). 



From these three widely separated localities I have seen plants 

 of so-called G. pusillus from Ardrossan only. The duplicate set 

 submitted to me by the collector permits me to state that the 

 late Baron confounded two very distinct species under the one 

 name, one being a state of Stenopetalum sphcBrocarpum, and the 

 other a plant agreeing fairly well with Benthara's description of 

 Geococcus pusillus. The first of these offers some points of 

 interest, which I will at once describe, whilst the nature of the 

 other will be considered in its relationship to other similar plants 

 observed elsewhere. 



Stenopetalum sPHiEROCARPUM. 



Under Geococcus pusillus, F. von Mueller included in the 

 Ardrossan List of Plants, op. cit., a dwarf state of this species, 

 differing in one particular only from the normal condition in 

 having cleistogamous flowers (though not observed by that 

 botanist). The flowers are more or less closed by the adpression 

 of the relatively large sepals, so that all the interior organs are 

 concealed. Each petal has a filiform claw, spathulately expanded 

 upwards, and terminated by a rather long filamental extension. 

 The latter in the dried specimens is spirally coiled in a horizontal 

 direction, and is included within the calyx. The capsules are 

 prolific in seeds, and though the pedicels are recurved, yet they 

 are not abnormally lengthened, so as to bring the fruit to the 

 ground. 



