[Pkoc. Roy. Soc. Victoria 28 (N.S.), I'art I., 1915.] 



Aim'. III. — Notes on certain aperies <>f Pterostylis. 



By R. S. ROGERS, M.A., M'.D. 



(With Plates VII.-IX.). 



[Read March 11th, 1915]. 



It has recently been discovered that botanists in Victoria and 

 South Australia when referring to the orchid Pterostylis cucullata, 

 Br., were dealing with two very distinct species of the genus. 



In South Australia the name has always been applied to the plant 

 known in Victoria as Pterostylis Mackibbini, F.v.M. This deter- 

 mination had the sanction of Tate. and. as I personally renieiniiei , 

 of Baron von Mueller also. This is a plant of sturdy habit, radical 

 leaves very large and generally crowded, flowers pubescent with char- 

 acteristic chocolate markings and usually rather docked sepals. 



In Victoria the name is retained for a plant of very different 

 appearance; a slender plant, whose leaves are not particularly 

 large and not crowded at the base, whose flowers are glabrous and 

 green without any brown markings, and whose sepals have long 

 caudae. 



Reference to the National Herbarium in Victoria shows that the 

 Baron held the opinion for very many years that the plant with the 

 brown facings was the true P. cucullata, Br. One of his earliest 

 specimens (1848) from St. Vincent's Gulf, South Australia, is 

 marked "P. cucullata, var.," and another bearing a much later 

 date (1882) from Mt. Lofty, S.A., is marked " P. cucullata" 

 What caused him to change his views in this matter is not clear, 

 unless it was the receipt of very striking specimens, almost a foot 

 high, collected by Mr. Mackibbin in King's Island in 1888. 



He published his description of P. Mackibbini in the Victorian 

 Naturalist in 1892 (vol. IX., p. 93). 



The inadequacy of mere verbal description and the great advan- 

 tage of illustrations becomes evident on reference to Brown's 

 original description of his species (Prod. 327), and that of Bentham 

 (Fl. Aust., VI., 357). Making the usual allowances for variations, 

 geographical and otherwise, these descriptions serve almost equally 

 well for the South Australian P. cucullata, or for the very dissimilar 

 Victorian plant known by the same name. 



In order to correct this anomaly an application was made to Kew 

 (England) for typical specimens of the true plant. This has afforded 



