# Hemianthus glomeratus



## Cavan Allen

I finally nailed down for certain what I suspected for a while now and especially since we collected honest to goodness _H. glomeratus_ in Florida, which looks and grows EXACTLY like what we've been calling _H. micranthemoides_ all this time. I hope to have some good photos of what I talk about below very soon. I was able to get the opinions of two botanists who are quite familiar with _H. micranthemoides_ to back up my own ID; as established and popular as this plant is, I didn't want to take any chances.

Also, the 'two-leaf' is also definitely not _H. micranthemoides_. The ID of that one has yet to be pinned down and is proving to be quite difficult. It may not be a _Hemianthus_ at all. Neal, do you know anything about the origin of this one? It would help immensely!

As far as I know, the current names are _H. micranthemoides_ and _H. glomeratus_ as opposed to _M. micranthemoides_ and _M. glomeratum_. More on that later.

_H. glomeratus_:
- wet depressions, standing water, drainage ditches
- chasmogamous flowers: they open completely and, in this case, are pollinated by insects. The flowers appear somewhat crown-shaped.
- acute calyx lobes - sepals are joined at the base and the lobes are pointed at their tips
- common in Florida

_H. micranthemoides_:
- tidal rivers, specifically in places that are exposed at high tide and frequently in sandy/gravelly areas where smaller streams meet the larger rivers
-cleistogamous - the flowers do not open and are self-pollinated
-obtuse calyx lobes - rounded at their tips. The entire flower appears distinctly round. 
-extinct?


----------



## NeonFlux

Mm-hmph. I see so these two plants are very identical, eh.. Interesting.


----------



## Cavan Allen

Such enthusiasm!  Yes, they are pretty much indistinguishable without flowers. On specimens anyway.


----------



## HeyPK

Spring break is coming up next week, and I will have the opportunity to take some close-up pictures of flowers of the the two leaved variety. Will post them here as soon as I get them. I still have the plant I got from Neil Frank growing emerse.

R33 GTR reported the 2-leaved variety from a river in Puerto Rico:
http://www.aquaticplantcentral.com/forumapc/plant-id/72895-need-id-plants.html


----------



## davemonkey

So, all our future recommendations for people to use "HM" in their aquascapes will now be replaced with "HG". 

That's awesome that you were able to nail this down...but kinda sad at the same time that HM may really be extinct. Happy hunting!


----------



## Cavan Allen

davemonkey said:


> So, all our future recommendations for people to use "HM" in their aquascapes will now be replaced with "HG".


Why I outta....


----------



## nfrank

Cavan,
Here is what i can tell you about my 2 leaf variant.

I obtained the plant from an ADA tank, while i was visiting Niigata, Japan in 1995.
When i queried ADA staff in 2000, they said via email:

"We call it "New Pearl Grass"- _Hemianthus micranthemoides _var. and we call the other species 'Pearl Grass'- _Micranthemum micranthemoides_ . We used to use _Hemianthus_, but many publication in Japan are using _Micranthemum_ more often. So we use now use _Micranthemum_."​
Here is a related Dec 2000 discussion on APD and one of my 1999 pictures that shows both variants in my old 125g tank. NPG is on right and what i have been calling HM is on left. (for now, we cannot say for sure what is the plant pictured on the left, since it was growing in that tank over 10 years ago and obtained from an unknown source... and perhaps, i obtained it during a NC collecting trip. I vaguely remember seeing it locally ). The USDA Data Base says that HM grows in the *NE* coastal States, from VA to NYS (which is not inconsistent with it appearing in NC) . This range for HM is also documented in Muenscher (1944) and Crow and Hellquist (2000). On the other hand, Godfrey and Wooten, Aquatic and Wetland Plants of Southeastern US (1981) does not mention HM, but does include M. glomeratum and says it is endemic to the penisular FL. Interestingly, HM was the plant of the month in TFH and consistent with what Cavan said, the writeup says "There are some reports that the plant has not been seen in its native habitat since 1941."


----------



## nfrank

i think i previously shared this picture of emersed growth of "New Pearl Grass." Without a macro lens i couldnt get a better picture of the tiny flower.


----------



## miremonster

Hello Neil,
thank You for the photo! I think, the 2-leaved Hemianthus here in Germany is the same as Your plant from Amano. I've gotten it ca. 10 years ago from Christel Kasselmann as Hemianthus micranthemoides, and Jozef Somogyi showed me the plant in a tank in Bratislava (Slovakia). Seemingly it was cultivated in Europe for decades but mostly the difference from H. "micranthemoides"=>glomeratus was not noticed or thought to be caused by growth conditions.

Here on p. 1 photos of my emersed 2-leaf Hemianthus above and H. glomeratus below:
http://www.aquaticplantcentral.com/forumapc/plant-id/61464-plant-id.html
The flower pics are not so good, but under the microscope the flowers of both plants looked very similar.

Btw., emersed 2-leaf Hemianthus looks very similar to emersed H. callitrichoides "Cuba"!

Heiko


----------



## HeyPK

Here is a picture of a flower of the 2-leaved variety, wet mount, taken through a microscope at 40X. The flower looks very much like the flower of H. glomertus. 4 sepals, 2 stamens (anthers broken off), a corolla with three prominent lobes, maybe another lobe that I can't see.


----------



## miremonster

Hello Paul,
the ends of the corolla lobes of Your 2-leaf Hemianthus are lacerated (don't know if the term is correct) just as in my plant. The corolla lobe tips of H. glomeratus are more acute.
[edit]and the upper lip of the corolla is apparently absent, typical of Hemianthus.


----------



## HeyPK

The picture of _H. micranthemoides_ in the USDA plants database (labeled _Micranthemum micranthemoides_) shows a flower with four stamens and rather different shapes to the lobes of the corolla. 









As far as I can tell, the flower of our two-leaved variety is similar to the flower for _H. glomeratus_. Shawn Winterton has a very nice macro picture of the _H. glomeratus_ flower:


----------



## Cavan Allen

A key and some information on _H. micranthemoides_ and _H. glomeratus_ is here on page 161:
http://books.google.com/books?id=7l...&resnum=3&ved=0CCYQ6AEwAg#v=onepage&q&f=false


----------



## Cavan Allen

nfrank said:


> Cavan,
> Here is what i can tell you about my 2 leaf variant.
> 
> I obtained the plant from an ADA tank, while i was visiting Niigata, Japan in 1995.
> When i queried ADA staff in 2000, they said via email:
> 
> "We call it "New Pearl Grass"- _Hemianthus micranthemoides _var. and we call the other species 'Pearl Grass'- _Micranthemum micranthemoides_ . We used to use _Hemianthus_, but many publication in Japan are using _Micranthemum_ more often. So we use now use _Micranthemum_."​


Hmmm... Well, it definitely isn't _H. glomeratus_ or actual _H. micranthemoides_, but I wonder how that name got attached to it. I suppose we could get in touch with them again to see if they know its original source.

I've actually thought about looking for it in NC. Its last know location was in southern VA (Chickahominy River - this exact location is now inundated by a damn, I'm told) and some commonly associated plants are found in NC, so I suppose it's not out of the question. if you could find a spot outside of the reach of any salt water. Perhaps looking in places slightly outside its known range could pay off. The Mattaponi River in VA is a good spot, I think, even though there are no specimens from there. 
http://en.wikipedia.org/wiki/Chickahominy_River
http://en.wikipedia.org/wiki/Mattaponi_River

I believe the TFH article is referencing the Plant Finder.


----------



## HeyPK

The stigma for H. glomeratus in the drawing in Pennell's book shows a two-branched stigma. In my wet mount picture, but the stigma seems to be made up of many tiny finger-like structures. Perhaps they are organized into two branches. It is a little hard to tell. There are possibly glandular cells on the filaments of the stamens. they can also be seen in Winterton's picture.


----------



## Cavan Allen

OK, time for some pics. All have been taken with a microscope camera. I may still need some practice with it, but I think they turned out well.

First is _Hemianthus glomeratus_ collected in Florida (I believe the corolla is missing): 









Next is _H. glomeratus_ sourced from general hobby circulation and grown by Ghazanfar:









Another flower from the same specimen:









Now, here is some REAL, honest to goodness Hemianthus micranthemoides collected in NY (1936 if I remember correctly):









Can anyone tell me what the differences are based on the earlier discussion?

Just for fun, here is the Cuban endemic _Hemianthus reflexus_. It's just a bit larger on average than _H. callitrichoides_.









The question of what the current genus is for these species appears to be unresolved. They are sometimes included in _Micranthemum_. For now, I propose we continue to include them in _Hemianthus_.


----------



## Ghazanfar Ghori

Is that from my pressing?! WOHOOO! I'm FAMOUS!


----------



## Cavan Allen

It is. Thank you for your contribution to science.


----------



## 4f1hmi

:yo:Hats off to all of you guys doing the hard work for us !


----------



## Ghazanfar Ghori

We need to get that two leaf version...


----------



## Cavan Allen

A photo? I could take one. It definitely isn't real micranthemoides, but what species exactly is proving to very difficult to pin down. Not knowing where it came from originally makes it doubly so. Might be undescribed.


----------



## miremonster

I wonder if the "Toro *****" one from Puerto Rico: 
http://www.aquaticplantcentral.com/forumapc/plant-id/72895-need-id-plants.html
http://amepr.createforumhosting.com/planta-del-rio-t6645.html
and Neil's and Paul's 2-leaf Hemianthus are the same plant.

And, has somebody already compared emersed 2-leaf Hemianthus and Hemianthus callitrichoides "Cuba"? I have yet to do that exactly, but at first glance they look alike. Emersed Hemianthus glomeratus is more different.


----------



## Cavan Allen

miremonster said:


> I wonder if the "Toro *****" one from Puerto Rico:
> http://www.aquaticplantcentral.com/forumapc/plant-id/72895-need-id-plants.html
> http://amepr.createforumhosting.com/planta-del-rio-t6645.html
> and Neil's and Paul's 2-leaf Hemianthus are the same plant.


I think they might be.

In the _Micranthemum_ indet file (species uncertain), I found about seven specimens of a plant that really, really looks like the '2-leaf'. Leaves are opposite. All were from the Dominican Republic and look like what we'd call _Hemianthus_ if the two genera are kept separate (and I suspect they should be). It could very well be the same as the plant from PR. Oddly, the flora I found gives only _Hemianthus callictrichoides_ and _Micranthemum umbrosum_ as occurring in the DR. This is evidently neither of them. Some very old labels on them had them as _Callitriche_ , but that's obviously not the case, and a newer annotation refuted that but stopped short of putting a better name on it (there's some really strange stuff on old specimens from the days before our more advanced understanding of plant relationships). Neither I or anyone else has had a thorough look at it, but I'll give an update if that happens. At least, this may be progress. A real mystery!


----------



## HeyPK

Cavan, What was the habitat of the _H. glomertus_ you saw in Florida? Streams? Still water? ditches? Ponds?


----------



## Cavan Allen

It was a bright green carpet in ditches and wet depressions. Even puddles in dirt roads. It was pretty dry when we went, but those areas are under water much of the year.


----------



## miremonster

Cavan Allen said:


> Some very old labels on them had them as _Callitriche_


When I first got the 2-leaf Hemianthus, it reminded me of a Callitriche 



Cavan Allen said:


> The question of what the current genus is for these species appears to be unresolved. They are sometimes included in Micranthemum. For now, I propose we continue to include them in Hemianthus.


In Cook 1996, Aquatic Plant Book, Micranthemum and Hemianthus are distinguished by present vs. absent (or rudimentary) upper lip of corolla. If this difference is consistently present, and if each genus is monophyletic (a natural group), surely there is nothing to be said against distinction between Micranthemum and Hemianthus.


----------

