Acorn, adder, ash...

acorn    adder    ash
beech    blackberry    bluebell    bramble    brook    buttercup
catkin    clover    conker    cowslip    cygnet
dandelion
fern    fungus
gorse
hazel    hazelnut    heather    heron    holly    horse chestnut
ivy
kingfisher
lark
magpie     minnow
newt
otter
pansy    pasture    poppy    porpoise    primrose
raven
starling    stoat    stork    sycamore
thrush
violet
weasel    willow    wren

— words removed from the Oxford Junior Dictionary in 2007 - via Dominick Tyler

See also Light, half-light