A Review of Important Literature Pertaining to Stipules

From these considerations Agardh concludes that there are two kinds of appenclicular organs instead of one, namely stipules and leaves.

Astaix.—Essai sur la Tb6orie des stipules, thi.se de l'Ecole de 'Marinade de Paris. 1-25. 1841. (Cited by Clos in Bull. Soc. Bot. Fr. 1 : 302. 1854. ) The conclusion is reached that the leaf is not a primitive ap pendage of the stipule and that the stipule is nothing more than an appendage of the leaf.

Hegel, E.—Beobachtung fiber den Ursprung and Zweck der Stipeln. Linnrea, 17: 193-234. 1843.

Hegel has studied the development of stipules in seedlings and in the growth of individual leaves. He believes, but does not feel ready to assert, that stipules are present in all Angiosperms in the earliest stages of growth. He therefore includes in stipular formations the ligule, ochrea, sheathing petiole and the supernu merary leaves of the Stellate. He concludes from his observa tions: 1. " That all the leafy organs of phanerogamie plants are di vided into two entirely distinct formations, the stipular and leaf formations.

2. " That the stipular formation arises from the base of the meristem tissue of the leafy axis, covering the summit, but always with a longitudinal cleft or one passing transversely across the apex.

3. " That perfect stipules are formed by the occurrence of two, four or more clefts in the original stipular sheath, giving rise to as many stipular leaflets.

4. " That the stipules receive their vascular bundles from the stem, and are usually parallel veined because of their forming originally a completely encircling sheath.

5. " That they serve always for the protection of the growing point and of the true leaves, when these are present, during their development.

6. " In all plants, organs adapted for protection belong not to the leaf•formation but to the stipule-formation.

7. " That stipules are to be regarded as a formation preceding the leaf-formation, since they appear before the leaves.

8. " That they belong primarily to a nodal ring distinct from that producing the leaves and situated either above or below it.

From these relations, as regards the leaf, interior and exterior stipules are distinguished.

9. " Interior stipules protect the formation of the following node and leaves. The leaf at the same node develops somewhat earlier or at about the same time.

10. " Exterior stipules develop before the leaf at the same node and therefore protect their own node with its leaf.

11. " As stipules are limited in the time during which they are functional, they lose their significance as soon as this purpose is fulfilled. They do not produce buds in their arils except in cases where true leaves are not developed." The following statement (p. 227) should be noted. " In some species of Thalictrum the membrane rising above the inner margin of the base of the petiole is the analogue of the ligule." Kirschleger, F.—Flora, 28 : 615. 1845.

The tendril of Cucurbitacere is regarded as a normal stipular formation.

Mercklin, C. E.

Entwicklungsgeschicte der Blattgestalten. 1846. (Translated into the French in Ann. Sci. Nat. (III), 6 : 215-246. 1846.) The statements of Mercklin are contrary to those of Revel. He says, " In all cases the stipules of the developing leaf appear as portions of the lamina.; it is only later, during the development and elongation of the petiole, that they become sufficiently sepa rated to be considered as distinct organs. In all simple leaves the stipules never appear at the same time with the first rudiments of the lamina ; they develop only with the inferior parts of the lamina including the petiole." " From my observations of stipules I conclude that in common with the leaflets they owe their origin to the common petiole and are formed later than the leaflets." Krause, G.—Einige Bemerke fiber den Blumenbau der Fumariame and Crnciferm. B. Crucifer e. Bot. Zeit. 4 : 137-150. 1846.

Stipules in the Cruciferre are considered (pp. 142-145) and the homology with stipules of the so-called glands at the base of the leaves is established by a careful series of observations upon their development. The glands of the bracts and floral organs are also included.* *See also Duchartre, Rev. But. 2 : 208. 1845-7 and Norman, Quelques Observ. de Morph. Veg. 1857.