The Nature and Origin of Stipules. 31 



small branches coming off at the base of the leaf from the main 

 lateral bundles. 



In Erigeron annuum (L.) Pers., for example, there are three 

 fibro-vascular bundles in the leaf-trace which pass up through 

 the central portion of the petiole, converging as it narrows. 

 But almost immediately on their departure from the stem each 

 of the lateral bundles gives off a branch in the same manner as 

 when true stipules are present. This branch forks at once and 

 supplies the wings of the petiole. In the cauline leaves (fig. 15) 

 its branches can be distinctl}^ traced into the lower lobes of the 

 leaf. The basal leaves of Aster undulatus L. show a condition 

 very closely similar to that found in Erigeron annuum (L.) Pers., 

 but in the cauline leaves there is a considerable modification by 

 which the large lobes of the base of the petiole (fig. IG) are 

 formed. The stipular bundle curves outward through the lobe 

 giving off branches which form a net-work supporting its paren- 

 chyma. It then passes up through the wing of the petiole and 

 into the basal part of the leaf. In Solidago juncea Ait., there 

 are eleven bundles in the leaf-trace and a stipular bundle is given 

 off on each side, supplying the margins of the petiole. Artemisia 

 vulgaris L. affords a very interesting variation. The lateral 

 portions of the primitive leaf have branched in a very curious 

 manner (fig. 17), forming several small leaflet-like appendages to 

 the base of the petiole. That they belong to the lateral portions 

 and are stipular in their character is shown b^^ the fact that they 

 are supported by branches of the stipular bundle which is given 

 off a little higher up than in Ei'igeroyi, passes on through the 

 wings of the petiole after giving off the branches and enters the 

 base of the blade as in other cases. This is the nearest approach 

 to the true stipular condition that I have observed among the 

 Compositas. 



The embrj'onic development of the foliar organ among the 

 Compositaj is in general too much abbreviated to give much evi- 

 dence in the consideration of the present question, and it should 

 be so expected from the position which the family holds at the 

 head of the vegetable kingdom. 



Petioles of the kind seen in this t3'pe of leaf-development are 

 very often short and usually more or less margined or winged by 

 the contracted basal parts of the lateral portions of the primitive 

 leaf. They are evidently' genetically different from the petioles of 



