Most chili plant species originated in South America. One thing that all pepper plants have in common is "capsaicin" in their name. Capsaicin is the ingredient in chili peppers that makes them hot. The heat is measured in Scoville units (named for Wilbur Scoville who developed this method). The measurement ranges from 0 to 300,000 with bell peppers on the low end of the scale and habaῆeros at the high end. The hundreds of varieties of peppers are categorized by their "bite" (amount of heat when bitten) sweet, mild, medium, hot and very hot.
Chili pepper plants have been growing wild in Central and South America for centuries. The first signs of domesticated chili pepper plants is thought to have been 6,000 years ago. Food particles were found on cooking utensils buried in archaeological sites throughout Central and South America. Chili peppers were introduced to Southeast Aisa in the 1500s. They came to dominate the spice trade around the world. Chili peppers are still in high demand today.
Sweet peppers are not considered chili peppers by many people because they have little to no bite to them. However, this group includes bell peppers, pimentos, relleno peppers and sweet banana peppers. The Scoville units for this group range from 0 to 1,000. The plants are recognized by their height, 18 to 24 inches high, narrow stems and branches, and large, dark green tear drop-shaped leaves. Bell peppers are large square-shaped fruits that have four distinct lobes and come in a variety of colors, most commonly green. Pimentos produce fruit that are 3 to 4 inches wide, 2 to 3 inches long, scarlet red and heart-shaped. Relleno peppers are 9 to 12 inches long and 2 inches wide at the bottom and red in color when ripe. Sweet banana peppers (Hungarian wax), as the name would suggest, are banana-shaped peppers that start as a pale green color and progress to orange and then red as they mature. The stems and leaves are similar in shape color to bell pepper plants.
Mild peppers are not sweet or hot. They have a mild flavor with a slight bite. They range in Scoville units from 1,000 to 3,000. Varieties included in this group are Poblano/Ancho (fresh/dried), Bermuda hot peppers, Ortega hot chilies and paprika. Poblano plants are tall and bushy with light green leaves with yellow veins. The fruits resemble chili peppers in that they are long and thin, turning from deep green to bright red as they mature. Bermuda hot peppers grow on a compact bushy plant. The leaves and stems are light green. The fruit grows to 3 inches in length and turn from green to red. Ortega hot chilies grow on a bushy deep green plant with long thin leaves. The green fruits grow between 6 and 9 inches long and remain very thin as they turn red. Paprika (known as a spice in Hungarian dishes) grows on a tall, bushy plant with dark green rounded leaves. The fruits are long and wide and as with others they are red when they are mature.
Christmas peppers, hot banana peppers (Hungarian hot wax), rocotillo and jalapeño peppers are examples of medium pepper plants. Scoville units for medium peppers range from 3,000 to 6,000. There is a small amount of heat from eating these peppers. They are often dried or pickled. Christmas peppers are considered ornamental but can be eaten. Christmas peppers grow on very small bush plants with very dark green stems and leaves. The leaves are long almost tear-dropped shaped. The fruits are small, upright and range in colors from green to yellow, orange and red. Hot banana peppers grow on plants identical to their sweet counter parts. The fruit of the hot banana pepper is the same color as the sweet banana pepper; however, they are shorter and wider. Rocotillo peppers produce small, bell-shaped fruits that grow in clusters. The plant is compact and bushy with varying ranges of light to medium green stems and leaves. The leaves are rough in texture and elongated. Jalapeño pepper plants produce green to red 2 1/2 inches to 3 inches long fruit. The plants are tall and deep green similar in size and shape to that of bell pepper.
Hot peppers range on the Scoville scale between 5,000 and 50,000 units. Serrano are the mildest, tabasco and cayenne are the hottest. Serrano pepper plants grow to 3 feet tall. The leaves are very distinguishable with short fuzzy green leaves. The fruits are small and grow in clusters. Tabasco pepper plant is compact and bushy that grows to a height between one and four feet. The fruits are approximately 1 1/2 inches long. Cayenne pepper plants are tall bushy plants that reach a height of 3 feet tall and 2 feet wide that produce long thin fruits.
Very Hot Peppers
These are the hottest of the hot chili peppers, with a Scoville range of 80,000 units to over 300,000 units. Peppers included in this group are chiltepin, habanero, rocoto and thai. Chiletpin pepper plants are low-growing plants with deep green stems and leaves. The bright red fruits (when ripe) grow upright in a round berry-like shape. Habaῆero pepper plants, considered the hottest of all the peppers, produce small square peppers. The plants are tall and bushy with a medium green color with long thin leaves. Rocoto grows on tall spindly plants that have small teardrop-shaped leaves and are light green in color. Thai pepper plants grow on small deep green plants with thing elongated leaves. They produce hundreds of small fruits on each plant.