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ADDITIONS TO THE ORCHIDACEOUS PLANTS OF 

 SOUTH AUSTRALIA. 



By R. S. Rogers, M.A., M.D. 



[Read September 13, 1917.] 



Plate XVII. 



1. Thelymitra azurea, n. sp. 



Plant 4 to 16 inches high ; with a rather long, narrow- 

 linear, often filiform leaf and a raceme of 1 to 12 deep bright- 

 blue (azure) flowers ; one acuminate cauline bract. Segments 

 of perianth veined, 5 to 6 lines long. 



Column rather widely winged ; the hood between the 

 penicillate appendages deeply tripartite, the lobes being 

 purple with yellow denticulate tips, the middle one shorter 

 than and imbricate over the outer ones; the hair-tufts 

 purple, borne upwards and forwards on two lateral expan- 

 sions of the column. 



Stigma large, ovate, occupying the greater part of the 

 anterior surface of the column, with a prominent glistening 

 rostellum in its upper part. 



Anther with a moderately long point, adnate to the 

 base of the middle and posterior lobe of the hood; pollen- 

 masses connected by distinct caudicle to rostellum. 



This plant is somewhat closely related to Thelymitra 

 ixioides, Sw., from which, however, it differs in its narrow 

 leaf, in the fact that it has one single acuminate bract on the 

 stem, instead of two clasping ones ; in the azure colour of its 

 flowers and in the absence of spots on the dorsal sepal and 

 lateral petals ; also in the much deeper clefts between the 

 middle and adjacent lobes of the hood and in the absence of 

 the crest of two or more rows of calli on the middle lobe, 

 which is characteristic of T. ixioides. Its time of blooming is 

 also about a month later than this latter species. 



Its slender habit and narrow leaf readily distinguish 

 it from the robust wide-leafed species of Mueller known as 

 T. epipactoides. In the latter plant the middle lobe of the 

 hood is higher than the adjacent lobes; in T. azurea it is 

 lower. The shot-silk colour of the flowers and the relatively 

 small stigma in Mueller's specie s are also points of 

 differentiation. 



Found blooming in great numbers between Mount Com- 

 pass and Victor Harbour on November 19, 1916. It appears 

 to be very localized in its distribution. 



The specific name refers to the beautiful colour of the 

 flowers. 



