144 Boeshore — The Morphological Continuity of 



beginning of parasitism. Such being the case, the second be- 

 comes that which we are inclined to favor. But the two-celled 

 . ovary of Scrophulariaceae and the one-celled ovary of the Oro- 

 banchaceae has been the barrier to such a connection with mor- 

 phologists in the past. 



As a preliminary, therefore, to subsequent studies and inves- 

 tigation it may be profitable to compare groups of parasitic and 

 saprophytic plants already known to us. To start with sapro- 

 phytic families first, it is well known as already shortly stated 

 above, that in the Burmanniaceae the green and least degraded 

 genera, such as Burmannia, have three-celled ovarv with cen- 

 tral placentation, while in Gymnosiphon and the most degraded 

 genera like Thismia and Arachnites the ovary has become one- 

 celled with deep to shallow parietal placentas. 



In the large family of the Orchidaceae as now recognized by 

 systematists the most primitive subdivision Apostasieae, has 

 subregular flowers, three to two stamens, and a three-celled ov- 

 ary to the pistil. In the more evolved subdivision Seleniped- 

 ieae, the flowers are decidedly irregular, the stamens are two in 

 number, and the ovary is three-celled. Root saprophytism in 

 its commencing stages is amongst these not uncommon. In the 

 division Cypripedieae, the stamens are still two in number, but 

 the ovary usually has become one-celled by varying stages of re- 

 duction in ingrowth of the carpellary margins by graded steps 

 that can well be traced. Saprophytism is a frequent feature of 

 their roots. In the division Orchideae, the flowers are most 

 varied and highly specialized, the stamens are now reduced to 

 one functional, the ovary is one-celled with shallow parietal pla- 

 centas. In this division all stages of condensing degradation 

 and loss of chlorophyll can be observed, till such non-chloro- 

 phylloid and greatly degraded genera like Neottia and Corall- 

 orhiza are reached. Unquestionably here a continuous process 

 of condensing reduction and degradation in the above more or 

 less related genera is correlated with increasing saprophytism, 

 all of this being associated with a gradual transition from three- 

 celled ovary to one-celled ovary with deep placentas and thence 

 to one-celled ovary with shallow marginal placentas. 



Again, the family Ericaceae when treated in the only appro- 

 priate morphological manner that explains the evolution of the 

 subdivisions satisfactorily, includes primitive shrubby plants 



