The style is a narrow extension of the ovary, usually pointing upwards, connecting the ovary to the
stigmatic papillae. It may be absent in some plants; in this case, it is referred to as a
sessile stigma. Styles generally resemble more or less long tubes. The style can be open (with few cells occupying the central part, or even none), featuring a central canal that may be filled with
mucilage. Alternatively, the style can be closed (completely filled with cells). Most plants with
syncarpous pistils (
monocotyledons and some
eudicotys) have open styles, whereas many eudicots and grasses have closed (solid) styles containing specialized secretory tissues, which connect the stigma to the center of the ovary. These tissues form a nutrient-rich cord for the growth of the pollen tube. When the
pistil consists of several
carpels, each of them may have a distinct
stylodium (sometimes seen as a pseudo-style) or share a common style. In
Iris and other species of the
Iridaceae family, the style divides into three "petaloid branches" (resembling petals), sometimes also called stylodiums, almost at the origin of the style and is called "tribrachiate". These are strips of tissue emerging from the perianth tube above the sepal. The stigma is a ridge or edge on the lower surface of the branch, near the tip of the lobes. Branched styles also appear in the genera
Dietes,
Iris, and in most species of the genus
Moraea. In
Crocus species, the style is branched into three "branches," forming a tube. Plants of the genus
Hesperantha have a spread-out branched style. The style can also be lobed rather than branched. Plants of the genus
Gladiolus have a bilobed style. In the genera
Freesia,
Lapeirousia,
Romulea,
Savannosiphon, and
Watsonia, the style has bifurcated and curved branches.
Attachment to the ovary May be terminal (apical), subapical, lateral, gynobasic, or . Terminal (apical) style position refers to attachment at the apex of the ovary and is the most common pattern. In the subapical pattern, the style arises to the side slightly below the apex. A lateral style arises from the side of the ovary and is found in
Rosaceae. The gynobasic style arises from the base of the ovary, or between the ovary lobes and is characteristic of
Boraginaceae. styles characterise
Allium.
Pollination Pollen tubes grow the length of the style to reach the
ovules, and in some cases
self-incompatibility reactions in the style prevent full growth of the pollen tubes. In some species, including
Gasteria at least, the pollen tube is directed to the
micropyle of the ovule by the style. == References ==