Identification guide of Amaranthus spp.

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Identification guide of Amaranthus spp.

Post by MWP admin » Mon Sep 03, 2007 10:17 pm

From a long and recent discussion about Amaranthus between myself, ruter and il-Pine, I am creating this post to give identification notes for the Amaranthus spp of Malta - at least the common 4or 5 species.
Last edited by MWP admin on Wed Sep 05, 2007 3:35 am, edited 1 time in total.
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Amaranthus hybridus L.

Post by MWP admin » Mon Sep 03, 2007 10:42 pm

Amaranthus hybridus s.l. L.
(Spleen Amaranth)

Synonyms:
Amaranthus hypochondriacus
Amaranthus chlorostachys
Amaranthus paniculatus


Stem dark green or purple, pubescent or nearly glabrous, slender, erect, branched.

Leaves bright green on both sides, paler beneath, slender petioled.

Inflorescence in linear-cylindrical spikes, axillary and collectively forming dense terminal panicles, ascending, spreading or drooping

Bracteoles 5, awn-tipped or sharply pointed, twice as long as the tepals

Tepals 5, narrow oblong or cuspidate.

Fruit is a small wrinkled circumscissile capsule called urticle.


Main identification features:

It has 5 narrow bracteoles (outer whorl) that are gradually tapered to a pointed tip and a set of 5 tepals (inner whorl) which are half the length of the bracteoles and broader, with an oblong shape ending with a short britle-like tip (mucronate)
Attachments
Amaranthus_ID.JPG
Flowers of Amaranthus hybridus
Amaranthus_ID.JPG (392.23 KiB) Viewed 26305 times
Amaranthus_ID2.JPG
Sketches of the tepals and bracteoles of Amaranthus hybridus. Adapted by S.Mifsud from free interntet sources
Amaranthus_ID2.JPG (35.85 KiB) Viewed 26286 times
Last edited by MWP admin on Wed Sep 05, 2007 5:15 am, edited 5 times in total.
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Post by MWP admin » Wed Sep 05, 2007 4:27 am

Amaranthus retroflexus L.
(Pigweed)


Stem green, robust, hairy to pubescent, branched and high up to 1.5m.

Leaves bright green long-petioled, drooping.

Inflorescence in cylindrical to conical spikes, axillary and collectively forming dense terminal panicles, mostly erect.

Bracteoles 5, tapering to an rounded tip.

Tepals 5, oblong or spathulate with a apical bristle (mucronate).

Fruit is a small circumscissile capsule called urticle.


Main identification features:

The oblong-ovate bracteoles (outer whorl) are gradually tapered to a blunt tip (not bristle-tipped) while the tepals (inner whorl) are half the length of the bracteoles and have an ovate shape ending with a short, bristle-like tip
Attachments
Amaranthus_retroflexus_ID2.jpg
Sketches and diagrams of A. retroflexus. Adapted by S.Mifsud from free interntet sources
Amaranthus_retroflexus_ID2.jpg (37.56 KiB) Viewed 26284 times
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Post by MWP admin » Wed Sep 05, 2007 5:13 am

Amaranthus viridis L.
(Slender Amaranth)

Synonyms:
Amaranthus gracilis

Stem is always green, mostly glabrous, slender.

Leaves Have a variably long petiole(1-10cm), egg-shaped to rhombic and often with a small notch at the tip. Several plants show a pale V-shaped patch on the upper side of the lamina.

Inflorescence in linear, slender and tall spikes, sometimes found curved down (drooping).

Bracteoles 3, pale-green, ovate to broadly lanceolate, membranous, equal or smaller than the tepals.


Tepals 3, short, spathulate to lanceolate, with a very short bristly tip, sometimes not present.

Fruit is a circumscissile capsule called urticle which when mature is often slightly longer from the clasping tepals.


Main identification features:

It has 3 short, elliptic bracteoles (outer whorl) ending with a blunt rounded tip and a set of 3 tepals (inner whorl) which are more or less same length as the bracteoles or slightly longer, but shorter from the mature fruit capsule. They have a spatulate shape and not conspicuously mucronate (bristle at tip very short or not present)
Attachments
Amaranthus_viridis_ID2.jpg
Sketches of the tepals and bracteoles of Amaranthus viridis. Adapted by S.Mifsud
Amaranthus_viridis_ID2.jpg (40.31 KiB) Viewed 26275 times
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