[Inspire91]

Hello everyone! A post about a collecting trip in Nagano, Japan, is up on my blog AquaBiota! Here is an excerpt of what you'll find there, for the rest click on the link below! Thank you for taking the time to check out this post ☺ Enjoy!
Inspire91

I wasn't sure what to expect, but my assumption was that we would just be collecting plants near the waterline. Upon first inspection around the waterline I didn't really see much of anything except a lot of tall grass. Though when I got closer to the water's edge, I looked into the water and saw this.

 

[miremonster]

Nice! Who has IDed it? IMO it may be a different species. Najas marina has usually spines also on the stem and not only on the margin, but also on the underside (abaxial surface) of the leaves. Looks mostly sturdier than that plant. But ID of Najas is quite difficult. I don't know how many species occur in Japan, but many of the Najas species of China are also found there:
http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=121596

 

[Inspire91]

@miremonster - This was the first time I had personally seen this plant, but my 3 friends who have dealt in plants for 15+yrs ID'd it for me.

 

[miremonster]

my 3 friends who have dealt in plants for 15+yrs ID'd it for me.

OK; despite the consensus, it may be interesting to check that by an ID key and botanical descriptions of the Najas species of the area. However, Najas marina is very variable. Apart from that, does this Najas and the N. japonica (Your blog) grow well in tanks?

OT: 7th photo in Your blog posting from May 22: http://img.photobucket.com/albums/v202/chazer/Elodeasp_zps1f553e8e.png
I believe it's not an Elodea but Hydrilla verticillata, native of Asia. Can be distinguished from Elodea and Egeria densa by clearly visible teeth on the leaf margins (very tiny, hardly visible with naked eye in Elodea spp. and Egeria densa) and internodes on the older parts of the stems being mostly longer than the leaves (vs. mostly shorter than leaves).

 

[Cavan Allen]

I think that probably is Najas marina. But I also agree with miremonster that it pays to do your homework and key plants out whenever possible to avoid mistakes. Much unnecessary confusion we've had could have been avoided had more people done that.