Q.23 Geitonogamy is a type of pollination, in which :

1. Transfer of pollen grains from anther to the stigma of a different plant
2. Transfer of pollen grains from anther to the stigma of chasmogamous flower
3. Transfer of pollen grains from anther to stigma of another flower of the same plant
4. Transfer of pollen grains from anther to stigma of another of cleistogamous flower

   Geitonogamy: Pollen Transfer Between Flowers of Same Plant

   Geitonogamy involves pollen transfer from anther to stigma of another flower on the same plant, making the third option correct. This form of self-pollination uses pollinators but yields genetically identical offspring.

   Introduction

   Geitonogamy type of pollination occurs when pollen moves from one flower to another on the same plant via pollinators or wind. Functionally cross-pollination but genetically self-pollination, it promotes inbreeding. This guide analyzes each option for botany exam precision.

   Option Analysis

   Geitonogamy (Greek: geiton = neighbor): Pollinator-mediated transfer within same plant, different flowers.

   • Transfer of pollen grains from anther to the stigma of a different plant: Incorrect. This defines xenogamy (true cross-pollination); genetic diversity via different genotypes.​

   • Transfer of pollen grains from anther to the stigma of a chasmogamous flower: Incorrect/Vague. Chasmogamous = open flowers; includes autogamy, geitonogamy, xenogamy. Not specific to geitonogamy mechanism.​

   • Transfer of pollen grains from anther to stigma of another flower of the same plant: Correct. Classic definition: same plant, different flowers. Pollinators visit multiple flowers; maize, cucurbits exemplify.

   • Transfer of pollen grains from anther to stigma of another of cleistogamous flower: Incorrect. Cleistogamous = closed, self-pollinating flowers (autogamy only); no external pollinators, cannot have “another flower” transfer.​

   Pollination Classification

   Type	Source	Agent	Genetic Outcome
   Autogamy	Same flower	No agent	Self (identical)
   Geitonogamy	Different flower, same plant	Pollinator/wind	Self (identical)
   Xenogamy	Different plant	Pollinator/wind	Cross (diverse) ​

   Key distinction: Geitonogamy reduces pollen export to other plants (display size effect: 10 flowers → 13% geitonogamy; 50 flowers → 45%).​

   Ecological Significance

   • Inbreeding depression risk despite pollinator involvement

   • Common in monoecious plants (maize), wind-pollinated species

   • Self-incompatible plants waste pollen on geitonogamy

   Exam Relevance

   GATE Life Sciences: Geitonogamy = same plant × different flowers. Mnemonic: “GEItonogamy = GEItone flower to another.” Contrast cleistogamy (closed, auto) vs. chasmogamy (open, all types).​