COMMON AMARANTH

Amaranthus retroflexus

Goosefoot Family [Amaranthaceae]

month8jul month8july month8aug month8sep month8sept

status
statusZneophyte
 
flower
flower8yellow
 
inner
inner8cream
 
petals
petalsZ5
tepals
type
typeZspiked
 
stem
stem8round
 
stem
stem8ribbed
 
toxicity
toxicityZmedium
 
sex
sexZmonoecious
 

21st Aug 2018, Langbridge Fm, Newchurch, IOW. Photo: (CC by 2.0) Geoff Toone
It grows to 1m high, here looking more like a dense bush, but it looks like they might be several separate plants(?).


21st Aug 2018, Langbridge Fm, Newchurch, IOW. Photo: (CC by 2.0) Geoff Toone


21st Aug 2018, Langbridge Fm, Newchurch, IOW. Photo: (CC by 2.0) Geoff Toone
The obverse of the leaves is pale green, possibly due to it being hairier on the back.


21st Aug 2018, Langbridge Fm, Newchurch, IOW. Photo: (CC by 2.0) Geoff Toone
The leaves are a darker-green.


21st Aug 2018, Langbridge Fm, Newchurch, IOW. Photo: (CC by 2.0) Geoff Toone
Below the single, long summit spike of florets, the shorter infloresent spikes below are in small groups.


21st Aug 2018, Langbridge Fm, Newchurch, IOW. Photo: (CC by 2.0) Geoff Toone
The dense inflorescent whorl of flowrrs are in an almost linear spike.


21st Aug 2018, Langbridge Fm, Newchurch, IOW. Photo: (CC by 2.0) Geoff Toone
The whorled inflorescences are held very close to the stem in a fairly dense way, but with gaps between in places.


21st Aug 2018, Langbridge Fm, Newchurch, IOW. Photo: (CC by 2.0) Geoff Toone
It is either a hairy or a densely hairy plant - with the hairs being on stems.


21st Aug 2018, Langbridge Fm, Newchurch, IOW. Photo: (CC by 2.0) Geoff Toone
It is monoecious with separate male and female flowers on the same plant. It has no petals, but it does have 5 tepals, although these look more like they have turned to fruits. They are interspersed by numerous and longer green spiny bracts (ouch!).


21st Aug 2018, Langbridge Fm, Newchurch, IOW. Photo: (CC by 2.0) Geoff Toone
The leaves are semi-glossy and somewhat wrinkled here. The main stems are angular, perhaps square with distinct grooves along them. Thinner stems supporting the inflorescence are more round and lack the grooves.


Hybridizes with :

  • Green Amaranth (Amaranthus hybridus) to produce Amaranthus × ozanonii which is found in just a few places in Southern Britain from 1959 onwards.
  • Indehiscent Amaranth (Amaranthus bouchonii) to produce Amaranthus retroflexus × Amaranthus bouchonii (which has no other name). 5 mixed populations of this hybrid and both parents were found in Cambridgeshire, most were sterile.

It is an alien neophyte becoming naturalised in waste places and tips. This specimen looks like it is on the top of a tip.

It's toxicity is medium to low, containing several potential toxins such as nitrates, oxalates and some unknown nephrotoxic and myacardiotoxic substances, which can all affect ruminent livestock - but mainly by the nitrates which are converted into nitrites within their rumen and which is rapidly absorbed and converted into Methemoglobin - resulting in a sudden onset of symptoms. But this usually requires the consumption of the plant over a period of between several days to weeks. Nitrate poisoning of these animals includes the sudden onset of tachypnea, weakness and recumbency. Animals which initially survive after several weeks recovery usually exhibit reduced renal function. Humans seem not to be affected as much, but then most are not daft enough to eat it in the first place.


  Amaranthus retroflexus  ⇐ Global Aspect ⇒ Amaranthaceae  

Distribution
 family8Goosefoot family8Amaranthaceae
 BSBI maps
genus8Amaranthus
Amaranthus
(Pigweeds)

COMMON AMARANTH

Amaranthus retroflexus

Goosefoot Family [Amaranthaceae]