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The stigma, together with the style and ovary (typically called the stigma-style-ovary system) comprises the pistil, which is part of the gynoecium or female reproductive organ of a plant. The stigma itself forms the distal portion of the style, or stylodia, and is composed of stigmatic papillae , the cells of which are receptive to pollen.
The stigma (from Ancient Greek στίγμα, stigma, meaning mark or puncture) is usually found at the tip of the style, the portion of the carpel(s) that receives pollen (male gametophytes). It is commonly sticky or feathery to capture pollen. The word "pistil" comes from Latin pistillum meaning pestle.
The stigma sits at the apex of the column in the front but is pointing downwards after resupination (the rotation by 180 degrees before unfolding of the flower). [ citation needed ] This stigma has the form of a small bowl, the clinandrium , a viscous surface embedding the (generally) single anther.
Close-up of a Schlumbergera flower, showing part of the gynoecium (specifically the stigma and part of the style) and the stamens that surround it. Plant reproductive morphology is the study of the physical form and structure (the morphology) of those parts of plants directly or indirectly concerned with sexual reproduction.
Diagram of flower parts. In botany, floral morphology is the study of the diversity of forms and structures presented by the flower, which, by definition, is a branch of limited growth that bears the modified leaves responsible for reproduction and protection of the gametes, called floral pieces.
Monocot flowers occur with parts having multiples of three; usually there are three stamen, three petals and three sepals (six tepals), and usually just one stigma. [18] However stamens in twos can be found in Cypripedioideae while single fertile stamens can be found in Philydraceae , Zingiberaceae , and as gynostemium in Orchidacaea .
Diagram of a blooming flower showing the position of the style. In botany, the style of an angiosperm flower is an organ of variable length that connects the ovary to the stigma. [1] The style does not contain ovules; these are limited to the region of the gynoecium (female organs of the flower) called the "ovary".
The stigma plays a role in guiding the sperm to a receptive ovule, in the case of many ovules. [11] Only compatible pollen grains are allowed to grow as determined by signaling with the stigma. In the pollen grain, the generative cell gives rise to the sperm, whereas the vegetative cells have a tube cell that grows the pollen tube.