380 



THE AMERICAN NATURALIST [Vol. XLVI 



of my cultures— a fairly large-flowered type (petals 

 about 2 cm. long) with relatively broad leaves and a 

 green stem the papillate glands 2 of which are colored red 

 by anthocyan. 



This form, biennis D, is widespread. It is common in 

 the suburbs of Boston, and I have seen it at Woods Hole, 

 P^mouth, and in the neighborhood of Philadelphia. 

 There is considerable variation in the breadth of the 

 leaves. Similar plants may also be found with clear 

 green stems indicating that the red coloration of the 

 glands may not always be a firmly established character 

 in the strains that show it. 



The plant which was the starting point of the strain 

 biennis D grew wild in the grounds of the Bussey Insti- 

 tution in company with a number of similar types. From 

 self-pollinated seed a culture of 51 plants was brought to 

 maturity in the summer of 1911, all the plants being alike, 

 even to the red coloration of the glands on the stems. 



Apparently there has been but little study of the surface tissues of 

 (Enothera with reference to their secretory or glandular functions. How- 

 ever, former statements of the absence of external glands in the group 



the Dicotyledons," Vol. II, p. 931, 1908). The forms of (Enothera with 

 which I am working {biennis, grandiflora, Lamarcliana. etc) have over the 

 younger portions of the plants more or less of a somewhat sticky moisture, 

 and the problem is from what cells do these secretions come. The hairs 

 on these plants are of two types, both unicellular, (1) short hairs attached 

 directly to the surface. (2) much lon^r and stouter hairs each arising 

 from the top of a papilla. The papilla in section is seen to consist of a 

 projection of the epidermis into which extends a number of hypodermal 

 cells. These hypodermal cells in younger portions of the plant are filled 

 with a dense viscous-like substance, as are also some of the epidermal cells. 

 On old portions of the plants these cells, like those of the hypodermal tissue 

 in general, are found to be quite empty. Thus the appearance of the contents 

 of the cells composing the papilla indicates that it is secretory in function 

 and I have consequently termed it a gland. The structure is important in 

 experimental studies since its coloration in some forms follows that of the 

 stem on which it lies (green or reddish) while in other forms the papilla 

 may be colored red upon green stems and ovaries. We trust that the evi- 

 dence presented above will justify the term gland which, if correct, is 

 preferable to the designations papilla?, pustules, tubercles, red tubercle-like 

 bases, red prickles, papillose based, red tuberculate, etc., that have been 

 applied by my correspondents to this structure, or to the hair. 



