31 



stipules, there being normally two stipules to each leaf, 

 one on each side of the petiole. These are very large 

 and leaf-like in Albizzia stipulate and the common Pea ; 

 sometimes they are like small bristles and are said to be 

 setaceous and in Capparis spinosa they are developed as 

 thorns. Stipules frequently fall off shortly after their first 

 appearance and often before the leaf to which they belong 

 is fully developed, as in Holoptelea integrifolia. In falling, 

 however, more or less noticeable scars are left behind and by 

 observing these it can be known that stipules were developed 

 and an idea formed of their shape and size. The large stipules 

 of many species of Ficus for instance leave ring-like scars. 



In Rosa the stipules are adnate to the petiole. In some 

 cases where the leaves are opposite a stipule of one leaf be- 

 comes united to the stipule which is opposite to it and which 

 belongs to the other leaf on the node, there thus being 

 apparently two large stipules at each node, situated between 

 the petioles of the leaves. Such a stipule is called an inter- 

 petiolar stipule and is well seen in Stephegyne parvifolia, where 

 each large stipule can be easily separated into its component 

 stipules along their line of junction, see Fig. 9, Plate VIII. 



In some plants in which there is only one leaf at each 

 node, the stipules cohering by their outer edges, entirely 

 embrace the stem and there is apparently one stipule opposite 

 the leaf. In some cases the stipules cohere both by their 

 outer and inner margins and thus form a complete tubular 

 sheath around the stem, called an ocrea, as seen in many 

 species of Polygonum. 



The leaflets of a compound leaf often have stipules which 

 are then called stipels. These may be seen in Desmodium 

 tiliaefolium, Fig. 1, Plate V. 



Leaves which produce stipules are said to be stipulate and 

 those which do not are exstipulate. Similarly leaflets which 

 produce stipels are described as stipellate. 



30. True leaves, like other organs, Metamor- 

 are often found to be metamorphosed, or altered in form, in 

 order that they may be able to carry out other work than 

 that usually performed by leaves. In Gloriosa superba the 

 apex of the leaf-blade is prolonged and becomes a tendril, in 

 the common Pea some of the terminal leaflets are trans- 

 formed into tendrils, in Clematis montana the petiole coils 

 round supports and serves as a climbing organ, in Berberis 

 Lycium the entire leaf is often transformed into a three- 



