46 
Groom . — On a New 
Beccari’s description be incorrect, the plant is doubtless merely 
another species of Petrosavia , the characters of which would 
require emendation. Hence any observations on the mor- 
phology and nature of Petrosavia are of interest. 
Beccari described the plant as parasitic on roots. Now 
there are many saprophytes, devoid of chlorophyll, amongst 
Monocotyledons, represented by all the Triuridaceae, nearly all 
the Burmanniaceae, and many Orchidaceae 1 . Dismissing the 
Corsieae, which are doubtless saprophytes, the remarkable 
fact becomes apparent that there is but one stated monocoty- 
ledonous parasite — Petrosavia. However, when it is borne in 
mind that for a long time botanists had failed to recognize the 
existence of many holosaprophytes, having assumed that those 
known were parasites, it would not be surprising to find that 
the same mistake had been made with regard to Petrosavia , 
especially as Beccari assumed that saprophytic Burmanniaceae 
and Triuridaceae were parasitic. So I asked Mr. Ridley if 
he would specially note whether or not the roots of his plant 
were connected with the roots of any other plants. In 
response Mr. Ridley pointed out the extreme difficulty in 
proving a negative when dealing with such fine roots, but he 
stated that he failed to detect any parasitic connexion. It 
may be stated at once that the histological evidence afforded 
by Protolirion goes to show that its ally Petrosavia is a 
saprophyte. 
Beccari gave a brief description of the histology of the 
stem of Petrosavia. He says, ‘ Una sezione transversale del 
caule presenta esternamente una parte corticale formata da 
4-5 strati di cellule assai grandi, poi viene un intiero e largo 
anello di fibre liberiane che in circa 9 punti, discosti fra di 
loro, si cambiano in fasci fibrovascolari ; il centro e ripieno da 
tessuto midollare molto lasso.’ 
1 Mr. J. G. Baker has kindly directed my attention to a probably saprophytic 
Iridaceous plant from Madagascar — Genosiris aphylla , Baillon. Bull. Linn. Soc. 
Paris, No. 145. 
