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iNaturalist:
Sugar maple spotting slows as Canada's fall color fades
iNaturalist:
Red oak spotting slows down as fall colors fade
iNaturalist:
This fuzzy forest moss is suddenly everywhere in Canada
iNaturalist:
Milkweed sightings stay high across Canada as autumn sets in
Why flower sepals stay smooth: matched growth and stiffness between cell layers
PubMed · 2026-09-01
Smooth leaf-like organs stay smooth when cells in both outer layers grow lengthwise and have similar stiffness. When one layer grows in conflicting directions and is softer, the tissue wrinkles and can sprout pointed bumps.
1
Ectopic expression of AS2 on the outer epidermis in the as2-7D mutant caused sepals to buckle early in development.
2
Buckling resulted from conflicting cell growth directions and unequal stiffness between the two epidermal layers.
3
Overexpressing the CDK inhibitor KRP1 in as2-7D aligned outer cell growth lengthwise, stiffened the outer epidermis, and restored smooth sepals; buckling also drove PIN1 convergence that initiates pointed outgrowths.
