12 MORPHOLOGY OF THE ANGIOSPERMS 



fused with the leaf primordium as this meristem develops on the leaf 

 buttress. In some compound leaves, appendages — stipels — occur at the 

 bases of the leaflets. Stipels are surely a part of the leaf, and are 

 evidence that stipules also are a part of the leaf. Stipules rarely occur 

 on cotyledons. They are occasionally present on perianth parts in some 

 of the more primitive monocotyledons — Melunthium, Zijgadenus — and 

 on stamens — Ornithogalum and other liliaceous genera and many of the 

 Bromeliaceae. Allium shows in its many species great variety in the 

 stipules of stamens, from well-developed to vestigial, and some species 

 have none. 



Stipules have been rather loosely classified on the basis of form and 

 relation to the leaf and stem. They are called lateral when they seem 

 to be lateral parts of the leaf, appearing like lobes of the lamina or 

 wings of the petiole. Lateral stipules that are borne on the stem inde- 

 pendently of the leaf are termed free (Fig. 3A, B, C)— Begonia, Vitis, 

 Hydrocotyle, Liriodendron; they are termed adnate where fused along 

 one margin to the petiole for all or part of their length— many Rosaceae 

 (Fig. 3D), Leguminosae. The term adnate is sometimes restricted to 

 stipules that are fused to the body of the leaf throughout their length, 

 as in the sheathing leaves of many monocotyledons; this type is also 

 called "vaginal." Ventral stipules are those whose margins meet on the 

 ventral side of the petiole — Artocarpus, Magnolia, some species of 

 Begonia. In axillary stipules, the margins are fused above the petiole, 

 forming a single leaflike pseudoaxillary structure. Axillary stipules have 

 also been called intrapetiolar. Intrapetiolar stipules are formed by the 

 union of stipules of two different leaves at the same node — Fuchsia, 

 Elatine. In the whorls of leaves of Galium ( Fig. 3C ) and related genera, 

 there are only two true leaves; the other "leaves" are intrapetiolar 

 stipules or, in part, individual simple stipules. Free stipules arise early 

 on the leaf buttress, close to the primordium of the blade and petiole, 

 but are isolated from the rest of the leaf during the enlargement and 

 maturation of the buttress. 



Stipules, common in most of the less advanced angiosperms, are 

 absent in most of the Sympetalae; they are present in some of the 

 Rubiaceae. Some families in the Archichlamydeae — Rosaceae, Legumi- 

 nosae — have stipulate and estipulate genera. In the woody Ranales, now 

 considered very primitive, there are estipulate families — Winteraceae, 

 Degeneriaceae, Eupomatiaceae, Annonaceae, Himantandraceae, Moni- 

 miaceae, Calycanthaceae, Lauraceae; and stipulate famflies — Magno- 

 liaceae, Chloranthaceae. Stipules commonly accompany the woody habit; 

 40 per cent of woody dicotyledons are stipulate, as contrasted with 20 

 per cent of herbs. 



In the monocotyledons, stipules, as paired, free appendages of the 



