82 0>" THE EXISTENCE OF TWO TOEMS IN SPECIES OP IISTII. 



seven dimorphic species of Linum ; but as this structure has been, 

 overlooked in such common garden-fiowers as L. grandiflorum and 

 L.flavum, it is probably of frequent occurrence. 



All the species, however, are certainly not thus characterized. I 

 have examined many specimens of L. catliarticum, and found in 

 all that the stamens and stigmas were of nearly equal height and 

 the same in all the plants. So, again, I looked, near Torquay, at 

 many ilowers of the wild L. usitatissimum or angustifolium (I 

 know not which), and there was no trace of dimorphism. Again, 

 I raised 111 plants from seed sent me from Kew, incorrectly 

 named L. Austriacmn ; the plants were tall and straight, having a 

 rather different aspect from the wild species seen at Torquay, with 

 extremely fugacious blue flowers : in all these plants the stigmas 

 stood on a level with the anthers or projected a very little above 

 them. I protected the flowers from insects ; but every one of the 

 111 plants produced plenty of seed. I mention this fact because it 

 had occurred to me that possibly a species might be dimorphic in 

 function, though not in structure. 



Lastly, Linum Lewisii, which is ranked by Planchon as a variety 

 of L. perenne, but which, now that we know the meaning of re- 

 ciprocal dimorphism, surely deserves specific honours, must not bo 

 passed over. According to Planchon*, the same plant bears some 

 flowers with anthers and stigmas of the same height, and others 

 with styles either longer or shorter than the stamens ; so that the 

 same individual plant is trimorphic. This, as far as I know, is a 

 unique case. Prom analogy we may pretty safely predict the 

 function of the three kinds of flowers: those with stigmas' and 

 anthers of the same height will be self-fertile ; those with these 

 organs of unequal height will require reciprocal fertilization. A 

 plant of L. grandiflorum or of the other dimorphic species, grow- 

 ing hy itself, could no more perpetuate its race than could one 

 sex of a dioecious plant, nor could any number of plants without 

 the aid of insects. A single plant of Linum Lewisii, on the other 

 hand, in all probability could propagate itself, even if no insects 

 were present, as probably sometimes occurs in its Arctic home. 

 If insects visited the plant, the flowers which were dimorphic 

 would be fertile one with another or with those on any neighbour- 

 ing plant. Thus the plant would receive the advantage of a cross. 



* Ilooker's London Joum. of Botany, 1848, vol. vii. p. 175. It is not im- 

 probable that the allied genus Sugonia is dimorphic ; for (p. 525) one species is 

 described " staminibus exsertis ; " another has " stamina 5, majora, stylos longe 

 siiperantia ; " and another is furnished " stylis staminibus longioribus." 



