Page 17 - Lesson Notes-Morphologyof flowering plant

(e) There may be variation in the length of filament as in Salvia and mustard.
iv. Gynoecium
Gynoecium is the female reproductive part of the flower and is made up of one or
more carpels or megasporangium. Megaspores are produced within the
megasporangium.’A carpel consists of three parts, i.e., stigma, style and ovary.
The stigma is usually at the tip of style and is the receptive surface for pollen grains.
Ovary is the enlarged basal part on which lies the elongated tube, the style.
The style connects the ovary to the stigma. Each ovary bears one or more ovules
attached to a flattened, cushion like placenta.
Depending on the number of carpel present may be free or united, gynoecium can be
of following types
(a) Apocarpous When more than one carpel is present, they may be free are called
apocarpous, e.g., Lotus and rose.
(b) Syncarpous When carpels are fused together, the gynoecium is called
syncarpous, e.g., Brinjal and Hibiscus.
The cavity enclosed by the ovary wall is called locule. The number of locules in the
ovary correspond to the number of carpels in the gynoecium, i.e., unilocular (only one
locule, e.g., Pea), bilocular (two locules, e.g., Tomato), trilocular (three locules, e.g.,
Ricinus), multilocular (many locules, e.g., Orange and lemon).
The arrangement of ovules within the ovary is known as placentation. The placenta
is a tissue, which develops along the inner wall of the ovary. The ovule or ovules
remain attached to the placenta.
The placentation can be of different types
(а) Marginal The placenta forms a ridge along the ventral suture of the ovary and the
ovules are borne on this ridge forming two rows is called marginal placentation, e.g.,
Pea.
(b) Axile When the placenta is axial and the ovules are attached to it in a multilocular
ovary, the placentation is called axile, e.g., China rose, tomato and lemon.
(c) Parietal When the ovules develop on the inner wall of the ovary or on peripheral
part, it is called parietal placentation. Ovary is one chambered but it becomes two-
chambered due to formation of the false septum, e.g., Mustard and Argemone.
(d) Free central When the ovules are borne on central axis and septa are absent, the
placentation is called free central, e.g., Dianthus and primrose.
(e) Basal In this type, the placenta develops at the base of ovary and a single ovule is
attached to it as in sunflower, marigold. The placenta develops directly on the
thalamus.

Insertion of Floral Parts (Forms of Thalamus)
The positions of different whorls of flowers are different. This is due to the position