Section # Water Plants
1. Filiform segments, none compound-like  
1.1 emersed leaves us. bract-like, much reduced:  
feather-like leaves coming from out of the sides Myriophyllum (water milfoil) (Haloragaceae; p. 307) Rose 0or4 4 4or8 0/0or4 4 0 1
leaves bunched toward the tip of unbranched stems, just below the surface of the water; in pools in freshwater swamps us. is overlooked until clusters of swollen flower stalks grow above water in spring and early summer Hottonia (featherfoil) (Primulaceae; p. 223) Dill
thread-like or larger lvs Najas (naiads) (Najadaceae p. 646) Water Plantain
1.2 emersed leaves foliaceous:  
  Proserpinaca (mermaidweed) (Haloragaceae; p. 309) Rose 0 3 3 3
thread-like or larger lvs Najas (naiads) (Najadaceae p.646) Water Plantain
2. filiform lvs, not simple; clustered branches; compound like arrangements  
2.1 emersed leaves us. bract-like, much reduced:  
leaves forming a cup pointed upwards algae
equivalent of compound lvs Ceratophyllum (coontail) (Ceratophyllaceae; p. 46) Magnolia
grows in streams with stony-bottoms Podostemum -- riverweed (Podostemaceae; p. 307) Rose
2.2 emersed leaves foliaceous:  
stems which grow under water have fine-forked lvs, the leaflets of which are uneven-ended Armoracia -- lake cress (Brassicaceae; p. 187) Dill
opp lvs thread-like lvs Zannichellia -- horned pondweed (Zannichelliaceae p. 647) Water Plantain
3. bigger leaf-like leaves, compound  
3.2 needlelike to oval, paired or bunched leaves on mainly flexible underwater stems  
opposite lvs, not whorled  
thin, but not linear, lvs Callitriche -- water starworts (Callitrichaceae p. 458) Aster
thin, sparse lvs (widely spaced) Crassula (Tillaea) (Crassulaceae p. 231) Rose
lanceolate lvs Didiplis (water purslane) (Lythraceae p. 311) Rose
spatulate, subsessile Elatine (waterworts) (Elatinaceae p. 141) Dill
spatulate lvs Ludwigia (marsh purslane) Onagraceae p. 313  Rose
whorled leaves  
linear lvs Hippuris (marestail) Hippuridaceae p. 458  Aster
elliptical lvs Micranthemum (Scrophulariaceae 471) Aster
spatulate lvs Elodea (common elodea) Hydrocharitaceae 637  Water Plantain

spatulate lvs Ludwigia (marsh purslane) Elodea (common elodea)

(Onagraceae p. 313) Rose (Hydorcharitaceae p. 637) Water Plantain

(leaf types based on Hotchkiss, 1972 )