Scrophulariaceae and Orobanchaceae 141 



dation-transitions from green strongly vegetative plants of in- 

 dependent nutrition, to others with feeble root saprophytism 

 and thence to highly degraded colorless and heterotrophic plants 

 like Thismia of Burmanniaceae, colorless genera like Epipogon, 

 Aphyllorchis, Neottia, and Corallorhiza in Orchidaceae, color- 

 less Monotropa and other genera of the Ericaceae, and the color- 

 less Leiphaimos in Gentianaceae. Now in all of these, distinct 

 and continuous transition is seen from five-celled, three-celled, 

 or two-celled states (Ericaceae, Burmanniaceae, Orchidaceae, 

 two-celled Gentianaceae) of the ovary to incompletely five-three 

 or two-celled, and ultimately a one-celled state with parietal 

 placentation. Such might, therefore, suggest that Orobanch- 

 aceae simply represents a greatly degraded offshoot series or 

 sub-family of parasitic habit that has gradually been derived 

 from Scrophulariaceae in which slow absorption of the ovarian 

 partitions has resulted in a one-celled state from a primitively 

 two-celled. If such be true, then varied morphological trans- 

 sitional characters should be traceable between Scrophular- 

 iaceae and Orobanchaceae, while correlated with this a graded 

 physiological parasitism and degradation should also be observ- 

 ed. It is the aim of the present thesis to demonstrate that such 

 is correct. 



In undertaking this, the writer might first review the varied 

 opinions held by previous observers. 



Review of Literature and Discussion 



Wettstein (1, p. 48) separates the Scrophulariaceae from the 

 Orobanchaceae and Gesneraceae on account of the one-celled 

 ovary in the last two. He states that a great many Scrophu- 

 lariaceae have close affinities with other families. "Die Orobanch- 

 aceae und Gesneriaceae lassen sich durch den 1 facherigen Frkn. 

 mit parietaler Placentation .... von den Scrophular- 

 iaceae unterscheiden. " He then states that clear connections 

 are shown in the genera Harveya, Hyobanche, and Buchnera of 

 Scrophulariaceae with Orobanchaceae. 



Beck (2, p. 128) makes this statement: "The Orobanchaceae, 

 which are frequently regarded as a parasitic side line of the Ges- 

 neraceae, are separated from the Gesneraceae through the per- 

 fect superior fruit, from the Cyrtandreae through the richly de- 



