Fabaceae [Leguminosae] - 12,000 species - world-wide distribution - over 300 species in the Texas flora - among the largest of Angiopserm families - three subfamilies [like the Rose family OR sometimes treated as an Order (Fabales) with 3 families] but most economically important elements are associated with the Faboideae [typical subfamily]. Unlike the Rose family, subfamilies are based on variation in the ANDROPERIANTH - the gynoecium is constant - one carpel with multiple seeds that will dehisce along TWO sutures = LEGUME = basis for conserved family name.
The family includes woody (trees and shrubs) and herbaceous species characterized by compound leaves in an alternate phyllotaxy and stipules. Flowers (Faboideae) show characteristic features (DO FORMULA) including connation and zygomorphy in the corolla and connation in the androecium. Most of the economically important species are self-pollinated (some outcrossing) annuals.
A major feature of the vegetative bean (comparable to the intercalary meristem of the grasses) concerns a symbiotic relationship with bacterial genera, especially Rhizobium.
Bacteria infect roots, producing NODULES - bacteria use resources that the plant could use BUT they also function to convert atmospheric nitrogen to a form (ammonia) that is usable by the plant - a classic symbiotic relationship. Elemental N2 is NOT available to plants - must be adsorbed through the roots as an ion (ammonia, nitrite, nitrate, etc). Thus, many legumes are equipped with tiny fertilizer factories (evolutionary success - many species, broad range). Plants of the Fabaceae are rich in nitrogenous compounds (protein) - actually function to fertilize the soil. Thus, like the grasses, the family includes an important forage (sun to plant to meat) component:
ALFALFA - Medicago sativa - cultivated across the globe - 33 x 106 HECTARES (hectare = 10,000 sq. meters or 2.471 acres - ALSO - A METRIC TON = 1000 kg OR 2205 lbs) - more land covered than any food legume - tetraploid perennial - possibly the only forage crop cultivated in prehistoric times - associated with diploid species of the near east = point of origin - probably spread with the diffusion of the domesticated horse - [ca. 3000 BP] - intoduced to US in 1850 - [grown in SA and MEX earlier - probably introduced by the conquistidores - winter hardyness bread into the crop at turn of the century - now - either in cultivation or as an ESCAPE - distributed across NA.
Other important forage legumes include the True Clovers (Trifolium) and Sweet Clover (Melilotus) with many other taxa.
Also, in addition to Rhizobium association - which is an ADVANCED phylogenetic feature - despite relatively primitive gynoecium (no syncarpy) - seed development is also 'advanced' in that embryo development is completed at ovule maturation, i.e., the seed contains embryo and little else. Thus, the legume seed, essentially a small, fully developed plant with little endosperm present at maturity, is rich in protein. 'PULSE' = grain legume
PEANUTS - Arachis hypogaea - South American genus [40-70 species - with a center of diversity in Brazil - 2n=2x=20 BUT two species [A. hypogaea and a wild type A. monticola [progentior or companion weed?] are AMPHIDIPLOIDS [=TETRAPLOID = 2N=4X=40] - British - 'ground nuts' - Why? - all members of genus are GEOCARPIC [fruits mature underground] - earliest archeological records are from Peru [4-5,000 BP], but original domestication was probably East of the Andes - by the time of Columbus the plant was distributed throughout SA and Mexico - early dispersal to Asia from Mexico by the Spanish and Africa vai Brazil by the Portuguese - distinctive African and Asian cultivars and close cultural connection forces this conclusion - OTHERS feel that Old World types may reflect pre-Columbian transport. First intro into temperate NA [1700s] was via Africa by slaves - thus, native americans produced the crop - WHAT DID JOHN HARVEY KELLOGG DO? = TEXT ASSIGNMENT.
SOYBEANS - Glycine max - 79 MMT - clearly the most important legume crop - use very early in northern China (7,000 BP-close wild relative - G. soya, domestication ca. 3,000 BP, diffusion thorughout Asia by 1500 BP) and limited to Asia until about the turn of the century - a 'cinderella' crop in the US (production has boomed over the past 50 years) - Why?
1. USDA plant explorers to China, Korea, and Japan - 1929 to 31 - ca. 4,000 seed accessions - then - WWII - shortage of butter - soybean oil for margarine - displaced other vegetable oils - residual 'cake' high protein foodstock for animals - crop rotation with maize - less N2 fertilizer - proved to be well suited for mechanized planting and harvesting - about 3/4 of the world crop now produced in the central U.S. plains states and southern Canada - BIODIVERSITY - about 3/4 of the 4,000 original collections from Asia have been lost [germplasm bank at the U. of Illinois] - current cultivars are based on about 11 of the original accessions
2. Low in carbohydrate, rich in oil, rich in
- in terms of amino acid content - 'COMPLEMENTATION'
In the US the crop is used primarily for oil and as domesticated animal food. Use is much more refined in Asia where the plant is culturally integrated and used as a primary food: CRUSHED, HEATED SEEDS, DECANT LIQUID = 'SOY MILK' [DRINK, NO-DAIRY INFANT FORMULA], SOLID = OKARA [COTTAGE CHEESE LIKE, SPONGY MASS THAT CAN BE EATEN. TOFU - boil soy milk in high salt concentration - coagulate protein to produce curds of tofu. SOY SAUCE - produced by soaking okara [previously encrusted by fungal hyphae] in salty water and filtering off the water - Henry Ford [direct consumption and use in US 1930s - energy relationships [move to primary foods - advances in processing - 'texturized vegetable protein - future may feature the soybean.
P. lunatus - 'Lima Bean' - dispersal vs. independent evolution problem - either central American with spread North and South or domesticated species derived from DIFFERENT founding wild populations in Mexico (Sieva type) and South America - very old records from SA - "Lima" referrs to Lima Peru - cyanogenic compounds in seeds - should cook before eating - toxicity is a characteristic of the family.
P. vulgaris - kidney, navy, green, string, black, wax, snap - component of the Native American trilogy - squash [ground vine], beans [climbing vine], and maize [erect - support - element]. POLYCULTURE [TRADITIONAL] VS. MONOCULTURE - NUTRITIVE AND ECOLOGICAL BALANCE]. Very early in both North [7000 BP at Tehuacan Valley - Mexico] and South American [7600 BP - Peru] - closest wild species are South American - again, independent evolution (anti-diffusionists) or single origin and cultural diffusion. 2nd most important grain legume (1st = soybean).
P. coccineus - Scarlet Runner Bean (now mostly an ornamental), but consumed in Mexico (2,200 BP - Tehuacan)
P. acutifolius - Tepary bean also early in the US southwest - 5000 BP in Mexico - only domesticated species of the genus native to west Texas
Old World Oldies:
Lentils - Lens culinaris and Peas - Pisum sativum - both date to 9000 BP and - with wheat and barley - comprised the foundation for the development of agriculture in the near east and - eventually - Europe. Lentils not of great importance today [1.5 MMT [soybean nearly 80 MMT], although Pisum at 9.4 MMT is 4th behind soybean, peanuts, and common beans.
Finially, Black-eyed Peas (Cowpeas) - Vigna unguiculata - only pulse firmly linked to African agriculture - most production still there - multipurpose crop (seed, sprouts, leaves) - like the peanut - introduced into the southeastern us by slaves.