172 Boeshore — The Morphological Continuity of 



Conopholis. No such continuity exists between the wholly 

 green autotrophic Gesneraceae and Orobanchaceae, nor are any 

 members of the Gesneraceae parasitic. 



2. During progressive parasitism in Scrophulariaceae and 

 Orobanchaceae commencing parasitism consists in a few of the 

 fibrous roots becoming enlarged toward their extremities into 

 parasitic haustoria, while other roots are still autotrophic in 

 relation. With increasing parasitism these secondary roots be- 

 come shortened and the primary root also condenses into a cen- 

 tral knob or swelling as can be traced successively in Gerardia, 

 Lathraea, Orobanche, Epiphegus, Conopholis and Aphyllon. 

 Ultimately, complete vegetative fusion and enlargements be- 

 tween primary root and ascending vegetative axis result in the 

 formation of a rounded tuber {Epiphegus) or greatly swollen 

 rounded or oval mass {Conopholis) difficultly distinguishable 

 from the enlarged roots of oak on which the last grows. 



3. In progressive degradation the elongated ascending leafy 

 axis of Gerardia or Bartsia shortens steadily, and in Harvey a and 

 Hyobanche becomes a short axis bearing reduced nonchloro- 

 phylloid foliage leaves. These are seen in Lathraea to become 

 the characteristic scales investigated by numerous observers. 

 In Orobanche the leafy axis is reduced to a short tuber that is 

 separated from the condensed primary root by a constricted 

 neck {0. cruenta), or the primary root and scaly axis become 

 continuous as in 0. minor. This by progressive degradation 

 becomes a slightly constricted root part below and a stem part 

 above, covered by tooth-shaped leaf-scales, or an oval tuber on- 

 ly, that is primary root below and tooth-scale stem above {Epi- 

 phegus). In Conopholis even this distinction is largely oblit- 

 erated. 



4. In the less parasitic types, e. g., G. flava, the leaves are 

 large green and actively vegetative, but by gradual stages be- 

 come in time small and scale-like in G. aphylla. In Harveya 

 and Hyobanche they are scattered along 2 to 6 inches of the con- 

 densing axis. In Lathraea, these scales are largely underground 

 colorless, or purplish-white, and extend over 1 to 3 inches of the 

 vegetative shoot. In Orobanche the brown, yellow or red scales 

 cover the short tuberous vegetative axis for one to one-fourth 

 of an inch. The same is true for Epiphegus, or the scales are 

 rather shorter for Aphyllon. In Conopholis the intimate fusion 



