Seed and Fruit Formation

seed formation - outer cell layers of ovule form seed coat

·         postpones development until more favorable conditions

·         protects young plant when it’s the most vulnerable

·         keeps stored food that keep young plant alive

·         adapted for dispersal

·         seed coat forms >> metabolic activities stop

o    germination can’t start until water/oxygen reaches embryo

·         seeds don’t germinate until appropriate conditions (heat, available nutrients, chemicals, pass through animal intestines, etc)

o    scarification - breaking down seed coat so that first root can emerge

fruit formation - helps angiosperm embryos survive

·         develops from flower ovary

·         different fruit types due to 3 layers (epicarp, mesocarp, endocarp) on ovary wall

o    follicles - split along 1 carpel edge

o    legumes - split along 2 carpel edges

o    samaras - not split, has wing

o    drupes - single seed in hard pit

o    true berries, more than 1 seed, thin skin

o    hesperidia - more than 1 seed, leathery skin

o    aggregate fruits - derived from multiple ovaries

o    multiple fruits - develop from flower cluster

·         fruit dispersal - mostly transferred by animals

o    fruits of maples, elms, ashes have wings >> distributed by wind

o    dandelions have light seeds >> wind distribution

o    coconuts, beach plants distributed by water