Leaf vegetables, also calledleafy greens,vegetable greens, or simplygreens, are plantleaves eaten as avegetable, sometimes accompanied by tenderpetioles andshoots. Leaf vegetables eaten raw in a salad can be calledsalad greens, where as leaf vegetables eaten cooked can be calledpot herbs.
Nearly one thousand species ofplants with edible leaves are known. Leaf vegetables most often come from short-livedherbaceous plants, such aslettuce andspinach. Woody plants of various species also provide edible leaves.
The leaves of manyfodder crops are also edible for humans, but are usually only eaten underfamine conditions. Examples includealfalfa,clover, and mostgrasses, includingwheat andbarley.Food processing, such as drying and grinding into powder or pulping and pressing for juice, may involve these crop leaves in a diet.
Leaf vegetables contain many typical plant nutrients, but theirvitamin K levels are particularly notable since they are photosynthetic tissues.Phylloquinone, the most common form of the vitamin, is directly involved inphotosynthesis.
Spinach, as an example of a leaf vegetable, is low incalories andfat per calorie, and high indietary fiber,vitamin C, pro-vitamin Acarotenoids,folate,manganese andvitamin K.[1]
The vitamin K content of leaf vegetables is particularly high since these are photosynthetic tissues, andphylloquinone is involved inphotosynthesis.[2] Accordingly, users ofvitamin K antagonist medications, such aswarfarin, must take special care to limit the consumption of leaf vegetables.[3]
If leaves are cooked for food, they may be referred to in theUnited States asboiled greens. Leaf vegetables may bestir-fried,stewed,steamed, or consumed raw. Leaf vegetables stewed withpork is a traditional dish insoul food andSouthern U.S. cuisine. They are also commonly eaten in South Asian dishes such assaag. Leafy greens can be used to wrap other ingredients into an edible package like atortilla. Many green leafy vegetables, such as lettuce or spinach, can also be eaten raw, for example, insandwiches orsalads. Agreen smoothie enables large quantities of raw leafy greens to be consumed by blending the leaves with fruit and water.
In certain countries of Africa, various species of nutritiousamaranth are widely eaten boiled.[4]
Celosia argentea var.argentea or "Lagos spinach" is one of the main boiled greens inWest African cuisine.[5]
InGreek cuisine,khorta (χόρτα, literally 'greens') are a typical side dish, eaten hot or cold and usually seasoned witholive oil andlemon.[6]
At least 80 different kinds of greens are used, depending on the area and season, includingblack mustard,dandelion,wild sorrel,chicory,fennel,chard,kale,mallow,black nightshade,lamb's quarters,wild leeks,hoary mustard,charlock,smooth sow thistle and even the fresh leaves of thecaper plant.
Preboggion, a mixture of different wild boiled leaf vegetables, is used inLigurian cuisine to stuffravioli andpansoti.[7] One of the main ingredients ofpreboggion areborage(Borago officinalis) leaves.Preboggion is also sometimes added tominestrone soup andfrittata.[8]
Botwinka (or boćwinka) is a soup that features beet stems and leaves as one of its main ingredients. The word "botwinka" is the diminutive form of "botwina" which refers to leafy vegetables like chard and beet leaves.[citation needed]
In thecuisine of the Southern United States andtraditional African-American cuisine,turnip,collard,kale,garden cress,dandelion,mustard, andpokeweed greens are commonly cooked and often served with pieces ofham orbacon. The boiling water, calledpotlikker, is used asbroth. Water in which pokeweed has been prepared contains toxins that have been removed by boiling and should be discarded.[9]
Sauteedescarole is a primary ingredient in theItalian-American dishUtica greens.
Postharvest diseases cause up to 50% losses of leaf vegetables. These arefungal,bacterial, and much less commonlyviral. The most important remedy is temperature-controlled storage, although it is also important to prevent mechanical damage as this provides entryways for pathogens. Uncontaminated water for washing vegetables is of lesser but still significant importance.[10]
Common bacterial pathogens include:Xanthomonas campestris pv.vitians,Pseudomonas viridiflava,P. cichorii, andP. marginalis,P. syringae pv.aptata,X. campestris pv.campestris,X. campestris pv.raphani,P. syringae pv.maculicola,P. syringae pv.alisalensis,Pectobacterium spp. includingPectobacterium carotovorum subsp.odoriferum andPectobacterium aroidearum,Dickeya spp.,Pseudomonas marginalis, andPseudomonas viridiflava.[10]
Common fungal pathogens include:Alternaria brassicicola,A. alternata,A. arborescens,A. tenuissima,A. japonica,Colletotrichum higginsianum,Colletotrichum dematium f.spinaciae,Microdochium panattonianum,Stemphylium botryosum,Cladosporium variabile,Cercospora beticola,C. lactucae-sativae,C. brassicicola,C. acetosella,Botrytis cinerea,Golovinomyces cichoracearum,Podosphaera fusca,Erysiphe cruciferarum,E. polygoni,E. heraclei,Sclerotinia sclerotiorum, andS. minor.[10]
Commonoomycete pathogens include:Albugo occidentalis,A. ipomoeae-aquaticae,A. candida,Hyaloperonospora parasitica,Bremia lactucae,Peronospora effusa, andPeronospora farinosa f.sp.betae.[10]
Fungicides such asprochloraz can be used to manage some of these.[10]
Pokeweed must be prepared properly or it is dangerous. ... The only parts of poke to be eaten are the young shoots and tender stem tips, along with their immature, meristematic leaves. These must be boiled in an ample pot of water and then drained. Eating poke raw can cause serious poisoning. ... [A] man became ill from drinking water in which mature poke leaves had been boiled (Jaeckle and Freemon 1981).
