杜父魚[tofugyo] sculpin (any fish of family Cottidae, inc. the bullheads and the miller's-thumb)
杜撰[zusan] careless
杜漏[zurou] careless
杜宇[hototogisu] lesser cuckoo (Cuculus poliocephalus)
杜夫魚[kakubutsu] fourspine sculpin (species of fish, Cottus kazika)

杜絶[tozetsu] stoppage
鎮守の杜[chinjunomori] grove of the village shrine
杜氏[touji] chief brewer at a sake brewery (after name of sake's alleged inventor)
杜若[kakitsubata] rabbitear iris (Iris laevigata)

お花見[ohanami] cherry blossom viewing
一花[hitohana] success
卯の花[unohana] bean-curd lees
雲鬢花顔[unbinkagan] beautiful woman (metaphorical)
黄花[kouka] chrysanthemum

火花[hibana] spark
花の木[hananoki] flowering tree
花瓣[hanabira] (flower) petal
花より団子[hanayoridango] dumplings rather than flowers

田鵑[hototogisu] lesser cuckoo (Cuculus poliocephalus)
杜鵑草[hototogisu] toad lily (Tricyrtis hirta)

山杜鵑草[yamahototogisu] lesser cuckoo (Cuculus poliocephalus) (esp. one living in the mountains)
杜鵑花[tokenka] satsuki azalea (Rhododendron indicum)