PLANTS AND PEOPLE
Hugh D. Wilson 

 Grasses

GRASSES I - POACEAE - (GRAMINEAE)- 620 GENERA, 9,000 SPECIES - MOST COMMON ANGIOSPERM FAMILY IN TERMS OF # OF INDIVIDUALS - TEXAS 122/523 - WORLDWIDE DIST.

35 DOMESTICATED (ONLY 5 FROM THE NEW WORLD), 12 OF MAJOR ECONONIC IMPORTANCE (ONLY 1 - FROM THE NEW WORLD) - 'CEREALS' - GREEK GODDESS CERES

NEW WORLD? - DOMESTICATED 'PSEUDOCEREALS' [AMARANTHUS, CHENOPODIUM], THUS NICHE OCCUPIED - FAMILY IS UBIQUTIOUS -

ALL HERBS [EXCEPT BAMBOOS] OF - GENERALLY - OPEN GROUND - WHY SO SUCCESSFUL - HAS TO DO WITH BOTH VEGETATIVE AND REPRODUCTIVE STRUCTURE OF THE PLANT

BASIC STRUCTURE: [Anemophily and bird dispersal - develop fully during lab session]

VEGETATIVE: STEM=CULM, ROUND, HOLLOW INTERNODES [USE ARUNDINARIA, SUGAR CANE (Saccharum officinarum) OR BAMBOO] -  LEAF, SHEATH, LIGULE - INTERCALARY MERISTEMS - USUALLY AT JUNCTION OF SHEATH AND BLADE, NEAR LIGULE - LEAF DEVELOPMENT IS DETERMINATE IN MOST PLANTS - MERISTEMS ELSEWHERE - GRASS LEAF CAN CONTINUE TO GROW AFTER THE BLADE IS LOST - 'TRADE OFF' APPROACH TO PREDATION - WHY?

MASSIVE HERDS OF UNGULATES 10,000 BP COVERING HUGE AREAS OF THE EARCH [AMERICAN PRAIRIES, EURASIAN STEPP, AFRICAN VELD] - RUMINANTS - 'RUMEN' BACTERIAL FERMENTATION TO REDUCE CELLULOSE TO SIMPLER COMPOUNDS THAT CAN BE DIGESTED - APPENDIX - NOW AGRICULTURE AREAS - WERE ONCE GRASSLANDS [MOST NOW ARE OCCUPIED BY GRASS AS WELL, BUT EITHER DOMESTICATES OR SEMI-DOMESTICATED SPECIES] - SPORADIC, SEASONAL GRAZING - THUS, ADAPTATION TO GRAZING VIA INTERCALARY MERISTEM [LAWNMOWERS]. - ALSO RHIZOMES, STOLONS, AND TILLERING - SPIKELET/FLORET/FLOWER

HUMAN INTERVENTION - FORAGE CROPS - COVER MUCH MORE CULTIVATED AREA OF THE EARTH'S SURFACE THAN GRAIN CROPS - PROBABLY MORE IMPORTANT AS A HUMAN FOOD RESOURCE - 'ALL FLESH IS GRASS' - MANY GRASS GENERA AND SPECIES INVOLVED - SOME NATIVE ELEMENTS OF OPEN AREAS [NORTHWEST U.S.] MANY INTRODUCED - 'SELECTED' FROM NATIVE POPULATIONS - LITTLE BREEDING OR 'DOMESTICATION' IN THE TRUE SENSE. THUS, MANY FORAGE GRASSES ARE 'INTERMEDIATE' ELEMENTS OF THE ETHNOFLORA - MANY 'ESCAPE' AND BECOME ESTABLISHED IN DISTURBED AND [SOMETIMES] NATURAL PORTIONS OF THE INTRODUCED RANGE

DIRECT GRAZING, HAY [AIR DRIED FOR STORAGE], AND SILAGE [UNDRIED, CUT - PLACE IN A CONTAINER [SILO] - AEROBIC TO ANEROBIC FERMENTATION - ORGANIC ACIDS GENERATED TO PRESERVE THE SILAGE - ENSILING.

Forge grasses:

Introduced: Paspalum dilatatum - 'Dallis Grass' AND P. notatum - 'Bahia Grass'

Native: P. plicatum - 'Brown Seed Paspalum' AND Schizachyrium scoparium - 'Little Bluestem'

REPRODUCTIVE: culm, sheath/ligule,'tiller'[with diagrams - repeat during lab]

FLORAL FORMULA: CA0 CO0 A3-6 (usually 3)G(2-3)

WIND POLLINATED VS. ANIMAL POLLINATED

CARYOPSIS - SEED+PERICARP - MANY GRASSES ANNUALS, THUS PHOTOSYNTHATE SHUNTED TO THE FRUIT - OUR INTERVENTION IS TO HARVEST THE FRUIT. 

PERICARP, TESTA [SEED COAT], ALEURONE LAYER [PROTEIN AND FAT], ENDOSPERM [STARCH], EMBRYO

See Rice animation 

FUNCTION: PERICARP/TESTA = PROTECTION [LIGNIFIED]

ALEURONE: PRODUCES ENZYMES THAT BREAK ENDOSPERM STARCH INTO SUGARS

ENDOSPERM: STARCH SOURCE

EMBRYO: THE REASON FOR ALL OTHER COMPONENTS

OUTER LAYERS = 'HIGH FIBER' = BRAN

ENDOSPERM = PURE STARCH

EMBRYO = PROTEIN - = 'GERM'

HUMAN SELECTION: NON-SHATTER AND EASE OF REMOVING FRUIT ONCE HARVESTED [THRESHING], NO GERMINATION DORMANCY, REDUCTION OF TESTA/PERICARP - INCREASE IN INFLORESENCE AND OR FRUIT SIZE - MODERN EFFORTS: 'DWARF' STRAINS [MECHANIZED HARVEST] WITH RIGID CULMS [LODGING]


Grasses II

GRASS GRAIN DOMESTICATES:

MAIZE, INDIAN CORN - Zea mays - [covered in lab last week - brief review] Paul Mangelsdorf [used to have an office in Butler Hall - 1930s] and Edgar Anderson - 'tripartite theory' for origin of maize [Maize, Teosinte, Tripsacum - Z. mays originated from a now extinct wild species from South America, Teosinte [weed that will cross with maize] arose from hybridization between Z. mays and another related genus - Tripsacum. Others - most recently Hugh Iltis - suggest that maize arose from Teosinte - HOW? - major differences between inflorescences of teosinte and maize! - one way - CATASTROPHIC SEXUAL TRANSMUTATION HYPOTHESIS [ILTIS] - maize ear originated NOT from a teosinte pistillate inflorescence BUT from a feminized staminate infloresence [HORMONES] - comparative molecular data support derivation of Z. mays from teosinte (Euchlaena mexicana, Zea mexicana, Z. mays subsp. mexicana, although many details remain obscure.

Z. mays is of tropical ancestry, is a monecious grass, probably originated in Mexico, diffused to SA and, later, SA strains were returned to Mexico in pre-Columbian times - hybridizsation and re-establishment of 'new' cultivars - basic types:

FLOUR FLINT DENT POP (fruit with different starch types)

    Flour - all 'soft' endosperm

    Flint - all 'hard' endosperm

    Dent - soft on the inside and hard on the out - thus, 'dent' at the top

    Pop - like flint - all 'hard' endosperm, but with a hard pericarp
 

Note - probably the most primative type is pop - maybe evolved prior to grinding for flour - amaranth balls

Native American processing highly refined - tamales, tortillas - combined with other [mostly plant] foods to produce a balanced diet - also MAIZE CHICHA - chew corn kernals - AMYLASE - break down starch for fermentation to a 'beer'

Modern maize goes into many products - mostly food for domesticated animals - also corn starch for industrial uses - 344 MMT (27 million bushels - current overview and comparison - USDA - feedgrains)

Barley - Hordeum vulgare - 1st [Fertile Crescent Syria/Iraq] ARCHAEOLOGICAL MATERIAL - 10,000 BP, SURELY CULTIVATED - BY 6,000 BP 2-ROW TYPES [THREE SPIKELETS AT EACH NODE, LATERIAL EITHER STAMINATE OR STERILE] ARE REPLACED BY FULLY DOMESTICATE 6-ROW TYPES - EACH FLOWER FULLY FERTILE IN EACH OF THE THREE SPIKELETS PER NODE - MAJOR GRASS OF THE EGYPTIANS AND GREEKS - OFTEN TOASTED AND GROUND INTO A MEAL FOR GRUEL - PROCESSING INITIATED THE THE NOTION OF MALTING - MOST BARLEY GROWN IN US TODAY USED FOR LIVESTOCK FEED [CAN FIND BARLEY FRUITS IN CANNED VEGETABLE SOUP - ALSO A MAJOR COMPONENT OF BEER. - 167 MMT

WHEAT (wiki taxonomy)- PROBABLY TAKEN INTO CULTIVATION WITH BARLEY, SLOWER TO BECOME DOMINANT, BUT BIOLOGICAL EVENTS EVENTUALLY ALLOWED IT TO BECOME THE WORLD'S TOP GRASS:

AA [n=7] x BB[n=7] = AB [sterile diploid hybrid] then doubling AABB [tetraploid - n=AB=14], then, AABB x DD = ABD [sterile triploid], then doubling = AABBDD = fertile hexaploid - 2n=6x=42

Triticum mononoccum (2n=14= AA) was 1st to be cultivated - non-shattering types evolved, now known as 'einkorn' wheat and relictual cultivation occurs in Yugoslavia and Turkey. AT NEARLY 3,000 BP - HYBRIDIZATION EVENT - SOME SPECIES OF WILD 'GOAT GRASS' (MAYBE T. speltoides or Aegilops speltoides) TO PRODUCE A STERILE HYBRID [AB] THAT DOUBLED ITS GENOMES TO PRODUCE THE TETRAPLOID LINE (AABB 2n=4X=28) = 'EMMER' WHEATS [T. turgidum var. durum) = durum wheat = free threshing [bases of glumes collapse at maturity] = allowed processors to AVOID TOASTING [AND PROTEIN [=GLUTEN] DEACTIVATION] to facilitate threshing - THUS, FREE-THRESHING TETRAPLOID PROVIDED THE INITIALED STEP FOR MAKING LEVENED BREAD

BUT TODAY THE DURUM WHEATS ARE USED MOSTLY FOR UNLEVENED PRODUCTS - PASTA, ETC.

COMMERCIAL WHEAT OF TODAY [T. aestivum] WAS PRODUCED BY HYBRIDIZATION BETWEEN 'EMMER' WHEAT (AABB] AND ANOTHER WILD SPECIES OF THE GENUS [DD] TO PRODUCE A STERILE [ABD] WITH DOUBLING [AABBDD-2N=6X=42] TO FORM THE HEXAPLOID

NOW 20,000 CULTIVARS GROWN ALL OVER THE WORLD - (wiki production)

INDUSTRIAL MILLING: WHOLE WHEAT FLOUR = ALL COMPONENTS OF THE CARYOPSIS, WHITE FLOUR - JUST ENDOSPERM [MUST BE 'ENRICHED'], GRAHAM FLOUR - ENDOSPERM AND GERM [EMBRYO] - MODERN TREND [FIVER NUTRITION] IS TO USE MINIMUM TREATMENT

RICE - Oryza sativa - world's most important crop (Wiki production/composition) - clearly Asian - don't know exactly where - biological types [indica=long-grained vs. japonica - short grained-guey] - in terms of cultivation - upland vs. wet[grown in standing water] modern milling of rice [brown to white] - japanese sailers - 'beriberi' = B1 dietary deficiency - also O. glaberrima - western Africa

Zizania aquatica - 'wild rice' NOT Oryza - New World genus of two species - more cultivated than domesticated - most harvest from wild stands in the Great Lakes region - great current demand - limited range - biodiversity - other species that could provide valuable germplasm to future breeders - Z. texana - only a few plants along the San Marcos River - under pressure from usage of the river - one of 26 Texas endangered species.

SORGHUM (review) - Sorghum bicolor - DOMESTICATED IN AFRICA, NOT KNOW EXACTLY WHEN OR WHERE - a multi-use grass - Grain types produce animal food, sugar (treat culms like sugar cane - specific variety - 'broom corn' variety with diffuse inflorescence - used in the production of brooms - forage and silage - wider use due to water shortage - drought resistant

OATS - Avena sativa - another 'secondary crop', perhaps the last domesticate of the eastern Mediterranean - ca. 2,000 BP - move through a ploidy series as did wheat - 2n=6x=42 - once a major food crop of northern europe - later was associated with the domestication and dispersal of the horse has a work animal - elimination of horses [mechanization] eliminated oats as a major crop - ALTHOUGH - current trends ['OAT BRAN' - HIGH FIBER DIET - WHOLE CARYOPSIS MILLED - toward oats as a primary food might change that. - 43 MMT

RYE - Secale cereale - 'secondary crop' - (2n=2x=14) weed in wheat and barley fields to domesticate [E. Anderson] - no glutins - no bread [rye or black break has wheat flour in it] - mostly planted for forage - (wiki production) see also - ergot

TRITICALE - ONE OF THE FEW DOMESTICATES PRODUCED IN HISTORIC TIMES - CROSSES BETWEEN BOTH TETRAPLOID AND HEXAPLOID WHEAT AND SECALE TO PRODUCE BOTH HEXAPLOID AND OCTOPLOID (x Triticosecale - intergeneric hybrid) not a major crop at this point in time but potential remains.  (see also Colchicum autumnale)


Return to Course syllabus
  22 Feb 2011