Q.You can easily study pollen germination by dusting some pollen from flowers such as pea, chickpea, Crotalaria, balsam, and Vinca on a glass slide containing a drop of sugar solution (about 10 per cent). After about 15–30 minutes, observe the slide under the low power lens of the microscope. What do you expect to see?
On a 10% sugar-solution slide, viable pollen grains germinate within 15-30 minutes and put out visible pollen tubes — this practical directly demonstrates the first step of pollen-pistil interaction (§1.2.3) outside the flower.
Why this works: a sugar solution approximates the sucrose-rich medium the stigma surface naturally provides, which stimulates a compatible, viable pollen grain to germinate — the same trigger that starts pollen-tube growth in vivo after pollination.
What you should observe under the low-power lens:
- Most pollen grains will appear as small, roughly spherical bodies on the slide (their genus-specific exine ornamentation may be visible).
- From a proportion of the grains, a thin pollen tube emerges through one of the grain's germ pores and grows outward into the sugar solution.
- The pollen tube carries the grain's two male gametes (the vegetative cell guiding the tube's growth, with the generative cell/its two sperm cells inside it) — exactly as it would when growing through the style toward the micropyle of an ovule in a real pollinated flower.
This is why the activity is a useful, simple classroom proxy for pollen-pistil interaction: it isolates and makes directly visible the germination + tube-growth step that is otherwise hidden inside the pistil.
Pollen tubes growing out of the germinated pollen grains — visible proof that the pollen was viable and has begun the same tube-growth process it would use inside a real pistil.
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