358 PLANTS STERILE WITHOUT INSECT-AID. Chap. X. 



V. tricolor. Sets very few and poor capsules. 



Jieseda odorata (Eesedaceae). Some individuals quite sterile. 



Ii. lutea. Some individuals produce very few and poor cap- 

 sules. 



Abulilon darwinii (Malvaceae). Quite sterile in Brazil : see 

 previous discussion on self-sterile plants. 



Nymphcea (Nymphaeaceee). Professor Caspary informs me that 

 some of the species are quite sterile if insects are excluded. 



Euryale amazonica (Nymphseacese). Mr. J. Smith, of Kew, in- 

 forms me that capsules from flowers left to themselves, and 

 probably not visited by insects, contained from eight to fif- 

 teen seeds ; those from flowers artificially fertilised with 

 pollen from other flowers on the same plant contained from 

 fifteen to thirty seeds ; and that two flowers fertilised with 

 pollen brought from another plant at Chatsworth contained 

 respectively sixty and seventy-five seeds. I have given 

 these statements because Professor Caspary advances this 

 plant as a case opposed to the doctrine of the necessity or 

 advantage of cross-fertilisation: see Sitzungsberichte der 

 Phys.-okon. Gesell. zu Konigsberg, B. vi. p. 20. 



Delphinium consolida (Banunculacese). Produces many capsules, 

 but these contain only about half the number of seeds com- 

 pared with capsules from flowers naturally fertilised by 

 bees. 



Eschscholtzia californica (Papaveracese). Brazilian plants quite 

 sterile : English plants produce a few capsules. 



Papaver vagum (Papaveracepe). In the early part of the summer 

 produced very few capsules, and these contained very few 

 seeds. 



T. alpinum. H. Hoffmann ( ( Speciesfrage/ 1875, p. 47) states 

 that this species produced seeds capable of germination only 

 on one occasion. 



C'orydalis cava (Fumariacea3). Sterile : see the previous discus- 

 sion on self-sterile plants. 



C, srtida. I had a single plant in my garden (1863), and saw 

 many hive-bees sucking the flowers, but not a single seed 

 was produced. I was much surprised at this fact, as Pro- 

 fessor Hildebrand's discovery that C. cava is sterile with its 

 own pollen had not then been made. He likewise concludes 

 from the few experiments which he made on the present 

 species that it is self-sterile. The two foregoing cases are 

 interesting, because botanists formerly thought (see, for 



