I remain pretty confused about identifying the varities of equisetum. As far as I can determing, both Hymale and Arvense appear in BOTH forms, the bush 'pine tree' and the leaveless 'snake grass' or 'joint-grass.' Chadwick says that arvense is the only equisetum that has joints that end with a brown edge. Photos of hymale on the web show it to have a brown edge to the segments.
See pictures below
http://plants.usda.gov/cgi_bin/topics.cgi
It shows pictures and distribution map for the various species.
I believe hymale is the naked stem species.
I've not heard the "brown edge" criterion before -- the criterion I've heard is that it be the vegetative, as opposed to the spore bearing stalk. And that comes from RS lectures. praetens seems to be the only species close enough to be confused and it might be close enough for use anyway.
For a more detailed botanical keying system see
http://hua.huh.harvard.edu/cgi-bin/Flora/flora.pl?FLORA_ID=12395
BTW, it may be too late to harvest now. At least we always try to harvest before summer solstice. You can order dried herb from JPI. But given that it grows in every state, it should be possible to find a local source.
I know what equisetum does (anti fungal wise). The interesting part is how and why (in fact the how and why for all the preps). And that leads to some deep thoughts about subtle natures.
David Robison
