In Larix pollen captured by the ovule and rested at the distal end of
the micropylar canal is transferred upward to the nucellus before it d
evelops a pollen tube. This upward movement occurs after the canal is
filled with secreted fluid, despite the fact that the pollen sinks in
the fluid. We examined the mechanism of the movement based on the morp
hology of the canal and its simulation using pipettes. When a water co
lumn moves upward in a waxed pipette, suspended particles also move up
ward carried by the meniscus. In L. x eurolepis the inner surface of t
he integument lining the micropylar canal is coated by a cuticle layer
. This layer is further coated by an integumentary membrane before the
fluid is secreted. This membrane, however, becomes distorted or disap
pears during fluid secretion. The exposed cuticle and the degenerated
hydrophilic nucellar apex may facilitate the movement of the meniscus
toward the nucellus as in the simulated pipette. Pollen is interpreted
to move by being carried by the meniscus when the fluid recedes.