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lovely pink grass stems (not), and 3 months work.Part 1.

Some time ago I did a blog in which I referred to some 'lovely pink grass stems' that are common around Hong Kong, and we have a few on the roof, whilst still in quarantine in late September. My how time flies....but I had a note saying that this was not a grass, but "an Amaranth (as in pseudo-cereal). :-) " Well, who am I to argue, especially when the person in question is a previous guest blogger and plant specialist Andre Jagger (whose illustrations and posters I simply adore).

So in the interest of accuracy - and beauty - we have the whole story here (thank you Andre, and I understand this took 3 thank you from all of us). ps Read it all...I guarantee you will learn a lot of new words!

Lagos Spinach, the Plumed or Silver Cockscomb.


Whilst examining the mangroves and mangrove associates on the Yam O Peninsula, Lantau Island, I came across a notoriously common herbaceous perennial, better known as a pantropical weed, from the family Amaranthaceae! Its native range is Tropical Africa but due to the fact that it tends to grow in a vast variety of landscapes it has since escaped its homeland and migrated far and wide. It can rise to human height but is more often less than 1.5 metres and found amongst grasses and other ephemeral weeds, on hillsides, at road sides - gutters, behind sand dunes and coves in places with a little fresh water. The leaves and flowers are edible and are grown for this use in both West Africa and Southeast Asia. This herb is the wild form or variety and is mentioned in many of the Asian and African Flora books.

It was a team of Nigerian scientists who examined Lagos spinach to find out the nature of its nutritive value. Indeed, it would make a good spinach and its abundance was a cheap bonus. It contains essential Amino Acids, of which five are at or in excess of World Health Organization prescribed requirements. These appear in the picture. I have nibbled on the leaves and as testimony I am still alive!

The plant in question is the famous Celosia argentea, apparently attributed to Carl Linneaus in 1753 in his 'Species Plantarum'. This work is available and reproduced at the Biodiversity Heritage Library, online. Sadly, this like so many attributions does not make it clear where the 'argentea' arose, you wont find it in the first edition of Species Plantarum. What you will find, however, is that Linnaeus moved some species in genus Amaranthus into the then new genus Celosia. I have to presume it was one of those until enlightened otherwise. The plant in this writing is the wild variety, perhaps known as C. argentea var. argentea. There are other Celosia species, varieties and cultivars, that are famous world wide for bringing bright colour to many gardens, these being the Feathered Cockscomb Celosia argentea var. plumosa and the Common Cockscomb or Crested Cockscomb (Celosia cristata) - a rather special floral fasciated species. This leads on to the cytology, the genetics of Celosia argentea. Should the Common Cockscomb be regarded as different from C. argentea? William Grant in 1954 (with follow up in 2011) examined the somatic chromosome numbers and revealed that the base chromosome number for Celosia species is 2n = 9. Given C. argentea has 2n = 72 as its chromosome number, C. argentea is Octaploid, eight times the base chromosome number of 9. ( In the animal kingdom, most animals cannot have more than two sets of chromosomes {the Diploid number} and will die very prematurely if they accidentally acquire more (a few counterexamples exist but those are pretty much limited to the fingers on one hand ... In certain specialised animal tissues this may occur but not so for the whole animal. Plants and Fungi, however, can almost do as they please and some genera flaunt it, especially the ferns!) Celosia cristata has 2n = 36, with the F1 hybrids of C. argentea and C. cristata being practically sterile with 2n = 54, 81 and 208. This established the former C. argentea var. cristata as the species C. cristata. Polyploidy (as in octaploid C. argentea) is often a source of genetic diversity and is considered useful.

In this picture above a full outline of the floral morphology takes place right from early raceme through the bud stage, onto the pre-anthesis bud and post-anthesis flower, then eventually to the seed pod and seeds. One thing of interest was the difference between the pre-dehiscent anthers and post-dehiscent anthers and the fused androecium. The stigma, according to this, 'Amaranthaceae, C. C. Townsend. Flora Zambesiaca 9:1. 1988', description reports two to three 'very short' stigmas but the writers personal view is that there is only one and it is lobed with up to three lobes.

The next question of interest was around the spiral(helical) phyllotaxis, the arrangement of leaves(petioles) around the stem and florets(pedicels) around the peduncle-rachis of the floral raceme. It is a good exercise to try to figure it out oneself, in both inflorescence and stem. As one moves to the apex (top most part of the stem or raceme) the helix appears to be left-handed. That is, tracing the helix from the previous to the next leaf on a stem or previous to the next pedicel on the peduncle in a raceme, the direction of addition of leaves or florets appears to be left handed (thumb up - direction of curved fingers). What is the actual kind of spiral? The writer has had a close examination of one or two plants and the leaves appear to have a 3/8 phyllotaxis, three rotations about the stem through 8 petioles until you return to the same longitude. One could say the same location, rather than longitude, if one joins the transverse sections of the stem at the initial petiole (1) and terminal petiole (9) by creating a doughnut! The difficulties in this estimation of phyllotaxis are close to insurmountable if one has just a few plants to look at. The trouble with leaf phyllotaxis is that the leaves have an axile distance between petiole insertions that varies from a few millimetres to 10 centimetres or more, depending on how rapidly the plant grows. This means it is only practical whilst the plant is very young - post seedling stage. The floret phyllotaxis has a different set of challenges. The first of these being that the pedicels are crowded along the peduncle, so close in fact that it makes it difficult to examine which one preceeds the next ... The second of these challenges is that of misalignment. In a 3/8 spiral phyllotaxis, the first, the ninth, the seventeenth, ..., petiole or pedicel should sit on the same longitude, there will be eight longitudes known as orthostichies (plural) [orthostichy (singular)]. So along the longitude one would see a regular pattern of petioles or pedicels following a 'straight line'. If the plant twists slightly or crowding dictates the obstruction to growth at a given location then a misalignment in an orthostichy will occur. So you have it! With the old peduncles of C. argentea flowers (the length of which can reach a phenomenal 47 cm - the writer cut one of such a length to examine) there are plenty of pedicel scars to bear witness to the spiral phyllotaxis. However it is rather difficult to track the exact type of spiral. A tempting trick might be to longitudinally slice the peduncle along an orthostichy (completely in half - so that one has two half cylinders and you can see both 'sides' of the orthostichy clearly for a trace and note to photograph the result so one can enlarge it to examine insertion points of pedicels). However, the writer found no clear orthostichy to be able to sever in the first place! Evidence from other Celosia species examined quite a while ago by others suggests there may be an irregular phyllotaxis, the cross examination continues ...

check in tomorrow for more amazing illustrations and poster and information.


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