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XVIII. — On the Development of the Flower of Pinguicula vulgaris , L. ; with 

 Remarks on the Embryos of ¥ . vulgaris, P. grandiflora, P. lusitanica, P. caudata, 

 and Utricularia minor. By Alexander Dickson, M.D. Edin. & Dublin. ; 

 Regius Professor of Botany in the University of Glasgow. (Plates XXVIIL- 

 XXX.) 



(Read 19th April 1869.) 



The order Lentibulariacese is usually described in systematic works as 

 exhibiting affinities, on the one hand with Scrophulariacese, which it resembles 

 in the bilabiate corolla, partial suppression of the andrcecium, bilabiate stigma, 

 and two-valved capsule; and, on the other, with Primulacese and its allies, with 

 which it agrees in having a truly free central placenta. 



Ltndley places the order in his alliance of Bignoniales, along with Scrophu- 

 lariacese, apparently following Mr Bentham, whom he quotes in support of the 

 supposed affinity between the families.* Others, again, more impressed with the 

 importance of the placental character, place the family near Primulacese, as has 

 been done by PAYER.f 



In the hope that the study of the development of the flower in Lentibulari- 

 acese might throw some light on the question of the affinities of the order, I 

 have, from time to time during several years past, taken up the investigation of 

 the organogeny of the flower of Pinguicula vulgaris, according as opportunities 

 occurred for collecting suitable material ; and I now venture to lay my results, 

 imperfect as they still are, before this Society. 



If a plant of Pinguicula vulgaris be examined during the flowering season, it 

 is found to exhibit a short axis, on which are crowded a variable number of 

 leaves, spreading out in a rosette-like manner upon the surface of the soil or turf 

 on which the plant is found. This short axis is terminated by a contracted 

 indefinite inflorescence, consisting of a variable number of ebracteate flowers with 

 long pedicels— an unstalked umbel, in fact, analogous to that in the ordinary 

 form of Primula vulgaris. Immediately below the inflorescence, a leaf-bud is 

 found in the axil of the last leaf. As the fruit ripens, the leaves of the main 

 axis gradually wither off, and the main axis itself decays ; the original rosette 

 becoming replaced in the autumn by a similar one, resulting from the develop- 

 ment of the axillary bud of its last leaf. On the approach of winter, the 



* Vegetable Kingdom, p. 686. f Lecons sur les Fam. Nat. des Plantes, p. 14. 



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