Chapter 9-Foods from Stems and Leaves

Transcription

1 Chapter 9-Foods from Stems and Leaves Monocot stem Eudicot stem Monocots Dicots Parallel Netted

2 All plants have growth points for shoot and root tips called apical meristems. Shoot apical meristems increase the height or length of shoots. Root apical meristems increase the length of the roots. Shoot apical meristems occur at the tips of the shoots, buried inside the developing leaves. Root apical meristems are much simpler, being primarily root tips. The secondary meristem result in growth in a lateral direction, such as the increase in girth of a tree.

3 Stems and Leafy Crops from Biennials Almost all plants have leaves, stems, and roots, but their sizes, shapes and arrangements differ. These differences are often correlated with life history or habitat. In biennials, (plants that require 2 years to produce seed), plants store carbohydrates in fleshy storage roots. In the second year, biennials use this stored food in the development of flowers, fruits, and seeds. Several biennial species are sources of both a root crop and a leafy crop. Farmers want mature, but tender leaves, or immature shoots for leafy crops. The plants are harvested when they are young, before the formation of storage roots. Farmers interested in a root crop wait as long as possible so the highest amount of nutrients will be translocated to the roots. The roots are harvested at the very end of the first year.

4 Stems and Leafy Crops from Biennials Divergence selection has occurred over time so that one set of cultivars produce the leafy crops and another set produces the root crops. Leafy vegetables from these species tend to have few calories and little protein. Leafy vegetables are typically consumed as salads.

5 Biennials Grown as Annual Leafy Crops-Cabbage and Its Relatives Foods in the Brassicaceae (mustard family) have pungent flavor from mustard oil glycosides (glycosinolates). Mustard oil glycosides are strong sulfur containing anti-predator compounds. Glucosinolates constitute a natural class of organic compounds that contain sulfur and nitrogen and are derived from glucose and an amino acid. Every glucosinolate contains a central carbon atom, which is bound via a sulfur atom to the thioglucose group and via a nitrogen atom to a sulfate group The array of vegetables produced by the modifications of the shoots of Brassica species exceeds that of other plant genera. Most of the commonly consumed vegetables in the mustard family come from Brassica oleracea. Brassica oleracea (Brassicaceae) is native to the north Atlantic coast of Europe. These vegetables are grouped together as cole crops (Latin calis = stem). Fossil evidence of the domestication of Brassica oleracea is lacking, but historical documentation suggests cultivation by the Greeks by 650 B.C.

6 Selection within B. oleracea occurred very early and lead to the development of various morphological forms.

7 Biennials Grown as Annual Leafy Crops-Cabbage and Its Relatives Wild plants were loose-leafed, bitter herbs that resemble modern kales. Early sea kales were adapted to coastal habitats where they were exposed to sea spray. The waxy layer that protected these plants is still evident in modern cole crops. These protective characteristics contribute to resistance to drought and cold. The common cabbage includes red and green cabbages with a tight head and smooth leaves. Headed cabbages form when lateral meristems of the primary shoot do not elongate and the inner leaves do not expand. The terminal bud remains buried deep inside the closely appressed leaves. Savoy cabbages are a distant variety and have loose, crumpled leaves. Savoy cabbages are a distant variety and have loose, crumpled leaves. Cabbages have been an important item in the diets of European peasants. They could be harvested late in the fall and stored over the winter.

8 Biennials Grown as Annual Leafy Crops-Cabbage and Its Relatives Sauerkraut has been an important method of preservation since 200 B.C. Sauerkraut and its Asian cousin kimchee produced sources of Vitamin C when fresh fruits and vegetables were unavailable. Other Brassica, cabbage-like crops include: -bok choy (B. chinensis) -Chinese cabbage -tatsoi B. campestris Brussel sprouts look like miniature cabbages, but are produced when axillary buds form small lateral heads. Brussel sprouts only date to about 1818.

9 Biennials Grown as Annual Leafy Crops-Cabbage and Its Relatives In kohlrabi, the swollen stem base is harvested. An early description by Pliny describes an expanded edible portion just above the roots. Descriptions of broccoli date back to the mid-16 th century, whereas the development of cauliflower is more recent. The two vegetables are derived from inflorescences of the cabbageplant and are treated as different varieties. Broccoli consists of a mass of fertile flower buds. Cauliflower is formed by a proliferation of stem tips and from a mass of tissue called curds. Chard, (Beta vulgaris subsp. cicla) has been eaten by humans in the Mediterranean region since prehistoric times. Selection for color has led to a palette of pigmented cultivars.

10 Biennials Grown as Annual Leafy Crops Celery (Apium graveolens; Apiaceae), and other species such as fennel are commonly grown as vegetable. The edible portion is the leaf petiole. Celery occurs wild today in temperate Eurasia. Greeks and Romans cultivated it, but our modern forms were developed within the last 300 years. Celeriac is the swollen hypocotyl of a celery plant. It is very popular in Europe and is eaten raw in salads or cooked as a side dish. Lettuce, chicory and endive belong to the Asteraceae (the sunflower family).

11 Biennials Grown as Annual Leafy Crops The most important plant that this family has contributed to the human diet is lettuce (Lactuca sativa). Some forms of lettuce have been cultivated as early as 4500 B.C.. Modern lettuce is derived from L. serriola, a biennial species of the Mediterranean region. Lettuce heads are formed by suppression of the lateral buds. The plants will bolt if not picked soon enough.

12 Biennials Grown as Annual Leafy Crops Endives and chicory have been used in salad as long as lettuce, but both plants are in the genus Cichorium. Chicory roots are roasted and ground and is used as a coffee substitute. Spinach, (Spinachia oleracea; Amaranthaceae) is native to western Asia was domesticated after the fall of the Roman Empire. Although popeye was strong to the finish cuz he ate his spinach, it was not the iron in the spinach, but the folic acid. Spinach is second only to liver in the amount of folic acid.

13 Vegetables from Bulbs Few plants are used in cooking across cultures as the Alliaceae (the onion and garlic family). Onions and shallots (Allium cepa), and garlic (A. sativum) probably originated in central Asia. The leek (A. ampeloprasum) originated in the near East. Almost all of the Allium species exhibit medicinal properties that relate to the sulfur-containing compounds, allyl sulfides. allicin

14 Study outline-chapter 9-Foods from Stems and Leaves Review: monocot vs. eudicot stem; monocot vs. eudicot leaf; apical meristems (primary) vs. lateral meristems (secondary) (Fig. 9.3) Stems and Leafy Crops from Biennials- Review: biennial How do farmers take advantage of the biennial habit? (Fig. 9.6) What family contains all of the cole crops? What are mustard oil glycosides (glycosinolates)? Biennials Grown as Annual Leafy Crops-Cabbage and Its Relatives Brassica (especially Brassica oleracea) Know origin/history and information about cultivation/domestication and uses. This list of vegetables would include: cabbage, Chinese cabbage, bok choy, tatsoi, brussel sprouts, kohlrabi, broccoli, and cauliflower. What part of the plant is consumed? Why was the process of fermentation to make sauerkraut and kimchee important? Biennials Grown as Annual Leafy Crops Chard, (Beta vulgaris subsp. cicla; Amaranthaceae) Know origin/history and information about cultivation/domestication and uses. What part of the plant is consumed? Celery (Apium graveolens; Apiaceae), Know origin/history and information about cultivation/domestication and uses. What part of the plant is consumed? Lettuce (Lactuca sativa; Asteraceae) Know origin/history and information about cultivation/domestication and uses. What part of the plant is consumed? Cichorium (includes endive and chicory) (Asteraceae) Know origin/history and information about cultivation/domestication and uses. Spinach (Spinachia oleracea; Amaranthaceae) Know origin/history and information about cultivation/domestication and uses. Vegetables from Bulbs Onions and shallots (Allium cepa); Garlic (A. sativum); Leek (A. ampeloprasum) (Alliaceae) Know origin/history and information about cultivation/domestication and uses.