CHAP. IV. LYTHRUM HYSSOPIFOLIA. 165 



est stamens project well above the mouth of the calyx, and 

 stand a little above the level of the stigma of the long- 

 styled form. In short, without entering on further details, 

 there is a close general correspondence in structure be- 

 tween this species and L. salicaria, but with some differ- 

 ences in the proportional lengths of the parts. The fact 

 of each of the three pistils having two sets of stamens of 

 corresponding lengths, borne by the two other forms, comes 

 out conspicuously. In the mid-styled form the pollen- 

 grains from the longest stamens are nearly double the di- 

 ameter of those from the shortest stamens ; so that there is 

 a greater difference in this respect than in L. salicaria. 

 In the long-styled form, also, the difference in diameter be- 

 tween the pollen-grains of the mid-length and shortest sta- 

 mens is greater than in L. salicaria. These comparisons, 

 however, must be received with caution, as they were made 

 on specimens soaked in water, after having been long kept 

 dry. 



Lythrum thymifolia. This form, according to Vauch- 

 er,* is dimorphic, like Primula, and therefore presents only 

 two forms. I received two dried flowers from Kew, which 

 consisted of the two forms; in one the stigma projected 

 far beyond the calyx, in the other it was included within 

 the calyx ; in this latter form the style was only one-fourth 

 of the length of that in the other form. There are only 

 six stamens ; these are somewhat graduated in length, and 

 their anthers in the short-styled form stand a little above 

 the stigma, but yet by no means equal in length the pistil 

 of the long-styled form. In the latter the stamens are 

 rather shorter than those in the other form. The six sta- 

 mens alternate with the petals, and therefore correspond 

 homologically with the longest stamens of L. salicaria 

 and L. Grcefferi. 



Lythrum hyssopifolia. This species is said by Vauch- 

 er, but I believe erroneously, to be dimorphic. I have 

 examined dried flowers from twenty-two separate plants 

 from various localities, sent to me by Mr. Hewett C. Wat- 

 son, Professor Babington, and others. These were all 

 essentially alike, so that the species cannot be heterostyled. 

 The pistil varies somewhat in length, but when unusually 



* ' Hist. Phys. des Plantes d' Europe,' torn. ii. (1841), pp. 369, 371. 



