PLANTS AND PEOPLE - Botany 328 - LECTURE NOTES - FALL 1997
Hugh D. Wilson - rm. 306, Butler Hall
25 September 97
 
Fibers II - fruit and seed fibers

Coir - Cocos nucifera - (Arecaceae or Palmae) - derived from thick, fibrous mesocarp [adapted for sea dispersal, thus resistant to sea water) - [fig. 16.13 in text] used in netting - not a good fiber - its use mainly based on ready supply of mesocarps from COPRA production - largest angiopserm seed - endosperm initially liquid (milk), as it matures, cell walls form around the nuclei and it solidifies as an oil-rich 'meat' around the testa - mounds bars

Luffa acutangula and L. cylindrica: - luffa - demonstrate unusual vascular system - another Cucurbitaceae - retting

Processing:

Retting: mostly for bast fiber, timed or controlled rotting to remove or disintegrate non-fibrous materials which are associated with the stem [cortex, pith] and vascular bundles [cambium, phloem]

Scutching: roll retted material to break the brittle woody material, then remove woody material (thick-walled xylem cells) by beating and scraping

Hackling: drawing scutched and retted material across a comb-like device to separate and align fibers

Decorticating: crushing and scraping to remove fibers in lieu of above, used mostly in leaf fibers

Ginning: unique to seed fibers, removal of the seeds

Fiber from Seeds: use blow gun: wood (gun barrel, darts), gum (stuff used to bind), cordage (vine bark used as wrapping), and fiber for attachment of gourd and (probably from Kapok (Ceiba - Bombacaceae), tropical tree, seed fiber, too fine to spin) - for packing. Note: ancient device - no DOMESTICATED plants involved - from with wild.


Cotton - most important fiber in the world today. Largest legitimate, non-food cash crop in the world economy - importance based on ease of large-scale production, mechanized processing and versatility of fiber (dyes well and is tough). Also has a FOOD use - cotton seed meal [ca. 25 million tons/year] - GOSSYPOL a problem

Wild cotton seeds are 'comose' with a covering of short hairs [linters] which are single cells that emerge from the surface [epidermis] of the testa or seed coat. Human selection has functioned to elongate these hairs [staples]. Domesticated species have both - linters are processed out and used in paper making

Gossypium (Malvaceae) - about 40 species with centers of diversity in Australia, southern Asia, Africa and the New World - two centers of domestication - Africa and south-central Asia (5, 000 BP in Pakistan), Mexico (ca. 6,000 BP), and South America (initial use ca. 10,000 BP, evidence of domestication ca. 4,500 BP). Genus studied cytologically by J. O Beasley of TAMU (Beasley Cotton Genetics Lab on Agronomy Road) - he defined GENOMES of Cotton

African/Asian ('Old World') cottons: G. arboreum and G. herbaceum - both diploids - 2n = 2x = 26 (Beasley genome AA) - origin unknown, possibly domesticated independently, early use in south-central asia with spread throughout the Near East and Europe by 1400s. Mostly replaced by New World cotton species, now grown primarily in India and Pakistan.

    Australian diploid wild cottons - Beasley genome CC

    Mexican/South American wild diploids - Beasley genome DD

Tetraploids: (AADD):

    South American Cotton: G. barbadense - tetraploid 2n=4x=52

    Mexican Cotton: G. hirsutum - tetraploid 2n=4x=52 (95% of world crop - species grown in Texas)

Mystery of Cotton - one of the genomes of the tetraploid cottons is that of G. herbaceum - an old world species (genome AA) - how did this happen? (review tetraploidy)

An ancient genus that has diploid species in Africa, Australia, and the Americas - divergence between these three groups evidently occurred as a result of long-distance dispersal.[genus age is ca. 24-33 my - most recent continuous distribution with Africa and Australia is 130-120 my - Gondwana supercontinent] - current notion: Either African genome (A) was present in South America and went extinct or (more likely) - seeds traveled from Africa to South America, hybridized with South American diploids (DD) - chromosome doubling (AADD) to produce the tetraploids, with the parential AA diploid going extinct.


Plant dyes are similar to plant medicinals in that ancient usage, very important at the time, has been replaced by chemistry and synthesis. Synthetic or aniline dyes have displaced natural products in terms of global markets but dye plants remain as items of historical interest and local usage. Various plants were brought into usage based on long-term human experimentation to maximize color and 'fixation' of the dye on cloth. The latter involves complex chemical bonding that often involved the use of specific substances - mordants - to make the dyes 'fast'.
 

Henna - Lawsonia inermis (Lythraceae) - dye with affinity to protein - use by Greeks and Romans as a hair darkener - still used as a base for hair colorants.

Safflower - Carthamus tinctorius (Asteraceae) - ancient dye plant that is still used

British 'Redcoats' of the American Revolution - 'madder' - Rubia tinctoria (Rubiaceae) - contains natural mordants

Annatto - Bixa orellana (Bixaceae) - red dye used originally as a hair-coloring paste, body paint and fabric dye by native Americans of the amazon lowlands now used as a coloring agent for margarine, cheese, and cosmetics.

TO LAB: for trip to LCP - focus on major families and 'gathering' - exam I next Thursday followed by a trip to the of Mid-Valley Cotton Gin - review ginning process in book prior to this trip - note input ['raw' cotton] and outputs [fiber and seed] and SCALE of operation in terms of technology and energy flow.
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