Vegetative Food I
(stem, leaves, and roots)
Human food derived from Grasses (Poaceae) and Beans (Fabaceae or Fabales) is, for the most part, derived from complex meiotic/reproductive activity that usually involves other animals (pollen vectors). Our harvest of stems, leaves, and roots is, on the other hand, derived from meristematic activity within a given plant. As we have seen, the meristem forms the foundation for many unique and characteristic aspects of the plant kingdom. Primary meristems (apical, lateral) form the basic structure of shoot and root whereas secondary meristems (derived from primary meristems to function in 'mature' sections of the plant) allow elaboration. The latter include intercalary leaf meristems of the grasses, the vascular cambium of woody plants (secondary xylem, phloem, and bark [Q. suber]), and the pericycle of roots (substitute for lateral meristems to form secondary roots).
Human use of grass and bean taxa is focused on utilization of post-reproductive resources (endosperm/embryo) that the plants develop to support their next generation. Our use of foods derived from meristematic activity represents, in most cases, utilization of resources that the plants sequester for the reproductive effort (biennials).
Brassicaceae: - mustard family - pungent flavor produced by a class of compounds GLUCOSINOLATES (mustard oils) that are characteristic of this family and evidently produced as an insect deterrent.
Brassica oleracea 'cole' crops (caulis = stem) - diploid (2n=2x=18) wild type now grows across western Europe but selection probably started along the Mediterranean coast (Greek - as early as 650 B.C.) to Europe - intraspecific adaptive radiation under human selection:
kale: var. acephala
probably the 1st type brought into cultivation - adapted to coastal habitats - salt spray - waxy layer that protected from salt damage still on modern cole crops - contributes to their resistance to drought and cold
cabbage: var. capitata
basal type - intermediate between kale and modern cabbage = Savoy cabbage (var. bullata) with looser, crumpled leaves. Modern types evidently developed in Germany around 1000 A.D. - suppression of nodal elongation - could be stored for some time - also shredded leaves could be preserved with salt in earthernware crocks over winter - SAUERKRAUT - a traditional folk defense against scurvy of the Dutch and English - anaerobic fermentation preserved vitamen C content of the cabbage. Captain Cook planted cabbage seeds in New Zealand on his 1st voyage with the hope that a fresh supply would be their on his return (dispersal event)..
brussels sprouts: var. gemmifera
evidently selected from a single mutant plant in 1750 - central meristem elongates, lateral meristems show supression of nodal elongation
kohlrabi: var. gongyloides - origin uncertain - expansion of the basal stem
broccoli: var. botrytis - more recent than cabbages or kales - flower buds (fertile)
cauliflower: var. cauliflora - flower buds (sterile)
also 'root' crops (hypocotyl [beneath the cotyledons, where shoot and root meet] partially involved):
Turnip: - Brassica campestris - (2n=2x=20) - possibly originated in India and dispersed as a 'useful weed' to the East and West with subsequent selection to produce extant vegetable crops. European cultivation as a root crop (most important modern usage is as an oil crop [rapeseed]) dates to 13th century with expansion as both table vegetables and livestock fodder with development of new varieties, esp. 'stubble-turnip' that allowed development of a crop in harvested grain fields (usually Secale). Many important cultivars evolved in China, Japan, and Korea, including Chinese celery cabbage, and Chinese white cabbage (pak-choi), both recognizable in Chinese writings of the 5th and 6th century.
Rutabaga: - Brassica napas - (2n=4x=38, possibly oleracea x campestris)Pre-Cucurbita jack o' lantern of Europe- larger (heterosis), stronger tasting than turnip - possibly derived from hybridizatin between cabbages and turnips - cultivars also selected as an oil seed crop.
Radish: - Raphanus sativus - (2n=2x=18) possibly Asian in origin, known from 4k bp in Egypt - as all above, also used as an oilseed crop (China). Cultivars familiar to North Americans (red, spherical) are derived from white, elongaged forms (oriental Daikon)
ASTERACEAE (COMPOSITAE) - no common biochemical feature, like mustard oils, but a biologically coherent (monophyletic) group linked by a common inflorescence type (capitulum) and classified into groups of related genera - tribes - (subfamilies for beans and roses), tribes for grasses and composites - major variants within ASTERACEAE= inflorescence types:
1. RADIATE ray
(ligulate) flowers + disc- Helianthus annuus
2. DISCOID - thistles - all disc flowers (thistles and relatives)
3. LIGULATE - all ligulate - milky sap (often defined as a subfamily)
Lettuce - Lactuca sativa (Asteraceae) - Very early in Egypt (4500 B.C.) and the med basin - closely related wild species there - have native species of the genus here, as well as introduced types - including the possible progenitor - L. serriola. (native to Mediterranean sand dunes and rocky slopes - phytochrome dormancy)- wild types are caulescent - domesticated types are not - different forms (head, romaine) are cultivars of the species. Historical records start in Greece (450 BC), to Rome by the 1st century AD with dispersal by Romans into northern Europe where it is well documented by the herbals. Spread eastward is less well defined, but known in Persia by 600 BC and China by 5th and 6th centuries AD. Your book discusses recent emergence (California) as a commercial crop via genetic reserves provided by wild taxa, including L. serriola.
Endives - Cichorium intybus and C. endiva - canned types in the US are produced from the perennial (intybus) whereas the salad green found in US supermarkets (greens) is taken from endiva. Root of Cichorium intybus is processed (roasted, ground) to produce 'chicory' for adding to or substituting for coffee.