82 ON THE EXISTENCE OF TWO FORMS IN SPECIES OF LINUM. 
seven dimorphic species of Linum; but as this structure has been 
overlooked in such common garden-flowers 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, catharticum, 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 flowers of the wild Z, 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. Austriacum ; 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 dimorphie 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 be 
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. From 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 by itself, could no more perpetuate its race than could one 
sex of a diccious 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. 
* Hooker’s London Journ. of Botany, 1848, vol. vii. p. 175. It is not im- 
probable that the allied genus Hugonia is dimorphic ; for (p. 525) one species is 
described * staminibus exsertis ; another has “stamina 5, majora, stylos longe 
superantia;"' and another is furnished “ stylis staminibus longioribus." 
