There is a question if Hygrophila sp. "Guinea" and H. pinnatifida are probably the same species:
http://www.guitarfish.org/2009/09/21/75g-1-5-months-in
They are really different species, in particular the emersed forms are very different.
-H. sp. "Guinea" in the emersed form has entire (not lobed) leaves, thicker stems, considerably bigger, differently shaped flowers and grows much higher. The emersed stems and leaves have inconspicuous short sticky hairs, and the plant has a very strong smell.
-H. pinnatifida is endemic of India, in the emersed form it is much more delicate and has deeply lobed leaves similar to the submersed ones. The emersed plant is conspicuously hairy and doesn't smell as strong as "Guinea". The flowers are much smaller and similar to them of H. corymbosa.
Submersed H. pinnatifida leaves are darker colored (upper surface olive green, brownish to reddish; pink underneath) also under low light conditions. The submersed plant develops runner-like shoots from the stem base.
Emersed H. sp. "Guinea":
http://www.aquaticplantcentral.com/f...ea-stinks.html
Emersed H. pinnatifida:
http://www.heimbiotop.de/hygrophila.html#pinnatifida
A drawing in a 19th century botanical publication (page up):
http://books.google.de/books?id=kj8A...tifida&f=false