MERISTIC VAKIATTOX IN PAPAVEK J)UBTUM 



299 



MEKISTIC VAEIATION IN PAPAVEK DUBIUM. 

 By T. a. Sprague, B.Sc, F.L.S. 



AccoRDiN^G to Fedde, the number of stigma-rays is 4-10 in 

 PaiJiiver dubiiim and 5-18 in P. Mhwas (Engl. PHanzenr. Papa- 

 verac. 294, 314; 1909). Owing to their large meristic range, these 

 species are exceptionally well adapted for the study of meristic 

 variation. The results of an examination of 5(3 plants of P. duhiun, 

 recently (July) found growing on weeds near the edge of a relatively 

 open shrubbery, suggest that the number of carpels is dependent to 

 some extent on the amount of food available when their primordia 

 arise. Out of 22 plants of one gathering, 12 vigorous ones, bearing 

 altogether 58 flowers, had an average of 5 '6 stigma-rays; whereas 

 10 weak or starved plants, bearing 30 ilowers in all, had an average of 

 only 4-7 rays. Further, the cajDsules and expanded Howers on a plant 

 usually had a higher average of rays than the flower-buds on the 

 same plant. The carpels of Nigella damascena afford a parallel 

 instance : " normally, that is to say in well-nourished flowers, they ai-e 

 five; in later flowers they are partly four and partly three " (Goebel, 

 Organography, ii. 538 ; 1905). 



The vigour of a plant may find expression in its size and weight, 

 extent of branching and consequent number of flowers, and in the 

 number of parts of the flower. A certain correspondence was to be 

 expected between the number of flowers on a plant and the average 

 number of stigma-rays, since these two numbers are presumably 

 correlated separately with the degree of vigour of the plant. How 

 fully this correspondence is realized is shown in the subjoined table, 

 which gives figures for 28 plants in which none of the capsules or 

 flowers had been destroyed. The other 28 plants had from one to 

 four capsules of flowers missing in each case, and are dealt with 

 separately. All unexpanded buds which were sufficiently advanced 

 for analysis were taken into account : — 



Comparison of the third and fourth lines of the table shows that 

 the average number of stigma-rays increases along with the number 

 of flowers per plant. The figures for the 28 plants in which one or 

 more capsules or flowers were missing were relatively irregular, as was 

 to be expected. Nevertheless, 18 plants with 2-5 flowers each had an 

 average of 4*9 stigma-rays per flower ; whereas the other 10 plants 

 with 6-9 flowers each had an average of 5*5 rays. The corresponding 

 averages for the undamaged plants were 5*2 for those with 2-5 flowers 

 each, and 6*0 for those with 6-8 flowers; the averages for the 

 damaged plants being lower, owing to the fact that the flowers 

 destroyed were mainly the older ones, which, as already pointed out, 



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