Amaranthacea???

[greenhorn]

Jan 07: Stem ca 3cm diam. and 50 cm long.

[MWP admin]

I have an exact similar specimen to identify and I am leaning towards A. viridis. Weber also mentions A. retroflexus and depends if petioles are hairy and number of flower segments

[MWP admin]

Here are my photos of what is probably the same species as greenhorn's.

Amaranthus viridis is my best guess but not sure.

[greenhorn]

The only difference, i can see, is the better quality of Your photos!!!

[MWP admin]

I also have in mind Amaranthus retroflexus L. So now back confused between A. viridis vs A. retroflexus, though the latter is more probable.

http://www.inea.uva.es/web/materiales/b ... encia4.jpg


and this for our German friends:
http://de.wikipedia.org/wiki/Zur%C3%BCc ... er_Amarant

[RutgerB]

Amaranthus retroflexus has a hairy stem, the perianth segments are like below.

If you trie to identify Amaranthus you have to harvest de seeds with the perianth segments. It is the only way to see it properly. Simply slap it against your hand or on a piece of paper, getting the result below. This photo is Amaranthus retroflexus, I dont think yours is.

[MWP admin]

Thanks Ru..

I have seen my first A. retroflexus this June and I agree that my (and greenhorn's) photo is not alike A. retroflexus. Without details of seeds and leaves, it is difficult to ID. Also the latter have large inflorescence, but it is not a determinate factor as are the seeds and stem/petiole vestiture (hairy or not)

Thanks for the advice, though I did not understood well what you mean by this statement:

"you have to harvest de seeds with the perianth segments"

[RutgerB]

I've got a language problem (got some Dutch in the sentence!). Hopefully by writing some more it will go away. By harvesting I meant; rub the plant hard so the seeds (and perianth segments around it) will fall out.

[MWP admin]

Got it !

No problem about lang. you are not alone

TNX

[IL-PINE]

In my opinion I would move towards [/i]Amaranthus retroflexus. The Amaranthus viridis should lack the sharp-pointed bracteoles.

Reference: http://herbarivirtual.uib.es/eng-med/especie/4277.html

[MWP admin]

Very interesting discussion pine and Rut.

Pine, regards the pointed bracts you are right, but then the stem is hairy while the ID pics posted are not hairy!

http://herbarivirtual.uib.es/eng-med/im ... 81120.html

I am trying to investigate other Amaranthus spp, but I wonder if it can be a hybrid between viridis x retroflexus.

[MWP admin]

This is Identified as retroflexus... Just for comparison purposes. it was 1.2m high and dense inflorescence

[MWP admin]

I have found a leaf of the species under investigation...
Stem glabrous. Blamey says retroflexus have hairy stems (above) and even Weber mentions the hair (but limits himself to the petioles).

If one takes a good inspection at the photo of the identified retroflexus, you could see hairs on the green stem (slightly unfocused and in the shade), though the petioles looks without hair to me. It seems that the hair in retroflexus is one of the key features for ID ...

I also found out that there are 4 subsp of A. hybridus!

[MWP admin]

I got involved in the ID now, and I am posting too much

Well, I found lots of pics of the A. hybridus, with and WITHOUT hairs. Have a look:





Website Ref:
http://pick5.pick.uga.edu/mp/20q?search ... s+hybridus

Hairless A. hybridus
http://www.hear.org/starr/hiplants/imag ... bridus.htm


Description of A. hybridus
http://www.illinoiswildflowers.info/wee ... igweed.htm


I'am leaning to A. hybridus at the moment but not settled

[RutgerB]

Sorry to go on about fruits/seeds/perianths/petals but you really have to look at this too for a good id. Made a new photo (sorry for the magnified hand!). Upper=A. retroflexus, Lower=A.hybridus (this one ssp. bouchonii). Same level of magnification.

[IL-PINE]

Regarding my earlier post -
I just wanted to exclude Amaranthus viridis.
Using stace for my ID:

1a) Tepals all tapered to an acute apex = A. hybridus group
1b) At least the inner tepals obovate to spathulate at apex though often with mucro (bristle tip). = A. retroflexus group.

Your 2 photos of the tepals describe these 2 points perfectly Rutger B! Thanks for your help!

[MWP admin]

Looking at the close up of my pics, I am seeing that all tepals are being gradually tapering to a sharp point. Hence I am getting confident onto an identification of A. hybridus.

What do you think?

[RutgerB]

I think so too. On your photo its hard to distinguish bracteoles from the perianth segments. But on some places on your close-up you can see them! The bracteoles are the longer spiny ones, the perianth the inner shorter.

[MWP admin]

Yes, we solved the case! I am quite sure that it is A. hybridus. Who wants to go for the subsp. ID LOL!

[MWP admin]

PS Pine:

1b) At least the inner tepals obovate to spathulate at apex though often with mucro (bristle tip). = A. retroflexus group.

I would not say inner and outer tepals but tepals and bracteoles respectively. There is only on whorl of tepals.

[IL-PINE]

I just quoted the keys in the book: New Flora of the British Isles by Stace.

I had previously no idea!

[MWP admin]

Ok.

What do you think about this guys (& girlz):
viewtopic.php?t=1200

[MWP admin]

From Rutger's lecture, this is my effort also as a thank you to him/her.

This must be Amaranthus retroflexus, seeds, bracteoles whorl, tepals, circumscissile capsule.

[RutgerB]

Thank you! I'm on a learning curve also. Nice pictures again. The overview about the amaranths is very instructive. Still some amaranths to go (Amaranthus graecizans, albus and caudatus)?

Rutger (Male )

[MWP admin]

Little by Little, they will be all tackled. Also Amaranthus blittoides in the list, but albus is probably not found anymore in Malta (or very rare)

[IL-PINE]

yep, found retroflexus in a field at Tal-Hlas in Qormi.