Re: Unknown plant

>  Rotala (rotundifolia??) Mine is
> a stem plant (narrower stem than Bacopa) about 1 - 2 mm, olive colored stem.
> The leaves are green or olive, darker on the undersides and arranged in
> pairs which alternatate at 90 deg. spaced about 5 mm at the base to very
> dense <1mm at the tips. The leaves of the main stalk attain a width of about
> 3 mm and a length of 10 to 15 mm and are oval shaped. The end of the leaf
> is hemispherical and the width is fairly uniform, tapering only slightly.
> There is no stem or stalk to the leaf, it emerges directly from the main
> stem with it's opposite mate.
Thanks to CrypDude who identified this as Ludwigia arcuata. I have no picture
in my book but the detail description matches so that's what I'll call it.

> I have one plant which I can't classify. It's a
> smallish stem plant, very green. The stem is about 2.5 mm and tapers
> toward the tip to about 1.5 mm. The leaves are very round up to 5 mm in dia.
> and are arranged in a spiral up the plant each at about 70 degrees from the
> previous. There is no pairing of leaves. Each leaf has a short stem emerging
> from the main stalk upto 5 mm in length. There has been no branching of the
> main stalk so far but the plant is only about 7 or 8 cm.
It's not Cardamine lyrata or Hydrocotyle leucocephala; I have H. leuco. which
has "scallopped" leaf borders, large leaves, rootlets at the leaf
nodes and 1-5 cm between nodes. The unidentified one has no rootlets and
the leaf borders are round. There is no concavity of the leaf edge where
the leaf stem joins it. I made a mistake in describing the spacing of leaves,
they alternate at about 125 degrees not 70! This means that every fourth
leaf will be 10-20 degrees advanced rather than straight up from the previous.
It could be that the natural tendency is 120 degrees and mine just has a little
extra twist in the stalk. The leaf stem is always close to the same size as
the leaf diameter and in some cases some of the leaves are almost a full
centimeter in diameter. I haven't read every description of every plant in
my book, but I've scanned all the pictures and the closest in leaf arrangement
and general shape (but not scales or details) is the Hydrocotyle. Maybe it's
a local BC aquatic plant that somebody put into an aquarium; it looks so
common, just like the weeds that grow in the shade in your lawn! :)
For a weed it's cute and growing so I'll try propagating it. It might
branch if I cut the top too.