Oenothera Lamarckiana Seringe. 



437 



§ 26. OENOTHERA LAMARCKIANA SERINGE. 



Oenothera Lamarckiana belongs to the subgenus Oma- 

 gra which some authors separate into a distinct genus. ^ 

 Its most important dis- 



tinguishing characters he in 

 the seeds which are irregu- 

 larly angular with ridges 

 along the angles and relatively 

 smooth spaces in between 

 (Figs. 97 and 98). These 

 characters make it possible to 

 distinguish them easily from 

 the seeds of all other subdivi- 

 sions of the genus Oenothera,'^ 



Fig. 97. Transverse section 

 through the seed of Oeno- 

 thera Lamarckiana; cc, the 

 cotyledons (there is no en- 

 dosperm) ; 0, epidermis; s, 

 areolar tissue with cavities ; 

 h, hard layer; ff, wings of 

 the seed. 



which are either smooth ex- 

 cept for small indentations, or with a sort of crown 

 at the upper end. The epidermis of the seed of Ona- 



^The most important special literature on this group is the fol- 

 lowing : 



E. Spach, Monographia Onagrearum, Nouv. Ann. Mus., IV, 



3, 1835. 

 S. Watson, Revision of the Extra-tropical North American 

 Species of Oenothera. Proceed, Am. Acad, of Arts and 

 Sci., Vol. VIII, 1868-1873. 

 Engler und Prantl, Die natilrl. Pflanzenfam., Ill, 7, p. 199, 

 where references to general literature will be found. 

 The following works must also be mentioned : 



J. ToRREY and Asa Gray, Flora of North America, Vol. I. 



1 838- 1 840, p. 492. 

 A. S. Hitchcock, Les Oenotheracees du Kansas, 1898. 

 H. Leveille, Monographic du genre Oenothera (as yet only 

 partly published). 

 Onagra is given as a subgenus in Endlicher, Genera Plantanim, p. 

 1 190 sub No. 61 15; as a genus in the Natilrliche Pftanzcnfamilicn of 

 Engler und Prantl, /. c.,p. 214; and also in Britton and Brown. An 

 Illustrated Flora of the Northern United States, Canada and the 

 British Possessions, Vol. II, 1897, p. 475. 



^The various subgenera of Oenothera are often accidentally 

 mixed up in botanical gardens but the above mentioned characters of 

 the seeds usually make it possible to sort them out again before 

 sowing. 



