Stipules, stipels, ligules and leaf-sheath

Modified basal elements in Dicroidium fronds (Corystospermales)

“…Functionally and morphologically similar structures occur among angiosperms in the form of laminar stipules. Unlike the cyclopter(o)ids and aphlebiae of fern and seed-fern fronds, however, stipules are paired outgrowths of the petiole base that are vascularized independently from the emerging petiole and leaf blade (Goebel, 1898(Goebel, -1901Lubbock, 1899;Sinnott and Bailey, 1914;Majumdar, 1956). As such, they do not represent modified elements of the blade, i.e., heteromorphic leaflets or pinnules, but rather a modification of the petiole base that is independent from the leaf blade.…”

“…It is generally assumed that the main functions common to cyclopteri(o)d elements on seed-fern fronds, aphlebiae of fossil ferns, and enlarged laminar stipules in angiosperms are to provide physical protection and an appropriate moist microenvironment for the young developing leaf (see, e.g., von Roehl, 1868;Stur, 1875;Lubbock, 1899;Goebel, 1898Goebel, -1901Potonié, 1903;Bower, 1910;Sinnott and Bailey, 1914;Florin, 1925;Hirmer, 1927;Majumdar, 1956;Crookall, 1959;Laveine, 2005;Galtier, 2005, 2011). In addition, enlarged stipules in certain angiosperm leaves may contribute significantly to photosynthesis; an extreme example is the extant legume Lathyrus aphaca L., in which the actual leaf blade is reduced to filiform tendrils, and photosynthetic function is carried out almost entirely by flattened, laminar stipules.…”

The formation of stipule requires the coordinated actions of the legume orthologs of Arabidopsis BLADE‐ON‐PETIOLE and LEAFY

“…Stipules are considered as outgrowths or appendages at the base of petioles and grow orderly on the stem nodes of flowering plants (Majumdar, 1956; Lacroix & Posluszny, 1989; Conklin et al ., 2019). Stipules generally appear in pairs opposite each other and have considerable diversity in size and architecture such as leaf‐like, spines or tendrils (Sharma et al ., 2012a).…”

Lígulas em Poaceae: uma abordagem conceitual, filogenética e ontogenética

“…Saint-Hilaire (1841) considers the ligule to be a fusion between the sheath and free axillary stipules at the apex, excluding the hypothesis that it would be derived from the fusion of two lateral stipules. A new type of mixed definition was proposed by Majumdar (1956), who describes it as a structure composed of stipules and the leaf sheath margin.…”