©ttginal 'Mxtitlt^. 



SIDE-LIGHTS ON THE STEUCTURE OF COMPOSITES. 



By Maxwell T. Masters, M.D., F.R.S. 



(Tab. 194, I.) 



The specimen of Heleniiwi autitmnale figured at Plate 194 I. has 

 a double interest, structural and historical ; structural in that it is 

 calculated to throw some light on the conformation and even the 

 hneage of Compositm ; historical in that it illustrates a condition 

 of things quite analogous to those upon which Linnaeus, in his 

 now little-read essay ' Prolepsis Plantarum' (1760), founded some 

 of his deductions. 



I purpose in the following communication saying a few words 

 on both these subjects ; and first as to points of structure. The 

 normal flower-heads of Helenium autumncde have the ordinary 

 character of the capitula of corymbiferous Composites, but in the 

 present instance, in place of each flower, existed a slender stalk, 

 with one or more j)airs of opposite, linear, remote bracts, and 

 terminated by a small flower-head with its involucel and contained 

 florets, the latter being variously modified. So far, then, the case 

 may be described as one of proiification of the inflorescence, a 

 condition not very unfrequent among Com230sites.* 



Coming now to the individual florets, it may be remarked that 

 they presented all stages of modification between mere tufts of 

 linear green leaves and the ordinary tubular and ligulate florets 

 proper to the species. It is not requisite to go into details as to 

 aU these modifications, as it will serve my present purpose to select 

 for comment a very frequent condition in which the following 

 appearances presented themselves : — Ovary wantmg ; pappus none ; 

 corolla yellow or vhescent ; in mode of development, form, vena- 

 tion, and relative position with regard to the stamens, exactly as in 

 normal flowers. The five stamens were perfectly free alike fi-om 

 the corolla and from one another, springing fi-om a prolonged 

 cyhndi'ical thalamus (hyi^ogynous). No trace of cohesion of the 

 anthers existed. Above the stamens the thalamus was prolonged 

 into a short cylmdiical stipes, bearing a pair of o^Dposite green 

 leaves, perhaps the equivalents of the carpels, but without any trace 

 of ovule, style or stigma. Above these the thalamus was again 

 prolonged, and generally terminated in a rudimentary flower-head, 

 the florets of which from then* size and distinctness offered an 

 excellent opjiortunity for tracmg the development of the flowers. 

 The florets may therefore, m general terms, be said to have been 



* See ' Vegetable Teratology,' section " Prolificatiou." 

 N. s. VOL. 7. [February, 1878.] f 



