The bean is an annual plant of the family Fabaceae. This is a huge plant family, with over 19,000 species, so there are many interesting facts about beans. Only orchids and asters outnumber the members of this botanical group. Among the bean plant’s many close relatives are peas, runner beans, broad beans, soya beans, peanuts, alfalfa, clover, lupins, and sweet peas. All these plants are grouped botanically based on the common structure of their flowers and other characteristics. All of them can be considered “Legumes,” although most of them are inedible and many are even poisonous.
The particular species we grow for bush, pole, and dry beans is Phaseolus vulgaris, (vulgaris, in Latin, always means “common”) and just this one species has a wide range of growing forms, sizes, and colours. Bush beans tend to form small, upright plants to 60cm (24”) tall, while pole beans may form vines as long as 2m (6’) or more. Filet beans are bred for very long, slender, and tender seedpods commonly known as haricots vert. Pole beans are widely considered to have a more intense “beany” flavour than bush beans. Flageolets (tender green bean seeds harvested at the semi-dry stage), are regarded by some to represent the ultimate culinary bean experience.
Many varieties of this species are also grown for dry beans rather than seedpods, and are usually grouped by colour. Black, pink, pinto, and white beans, along with red kidney beans and a few other groups include close to 2,000 named varieties. Because beans can be grown and dried for storage and then reconstituted as a healthy staple, they were a very sensible crop for early farmers, and many have long and complex histories.
Several bean varieties can be traced back to the pre-Columbian period, and were highly regarded by Meso-Americans as a sacred gift. Beans were grown in an early form of permaculture as part of the “Three Sisters,” along with corn and squash. These plants were easy to grow, easy to harvest, and in most years, highly productive. Corn was grown as a support for pole beans, with squash grown in between rows, where it would be warmer, more productive, and act as natural mulch against weeds.
After European contact, many bean varieties became staples in Mediterranean and western European cuisine. The wide, flattish, stringless “Romano” beans of Italian heritage are coveted for their consistent heirloom flavour. In the US, green beans were known as string beans or snap beans and became popular because they could be canned or frozen for long storage.
All beans are high in starch, protein, dietary fibre, and a host of minerals, such as potassium, iron, selenium, and molybdenum. Green beans, whether grown on a bush or vine, are very high in vitamin C and calcium. When reconstituted and cooked, dry beans are very high in starch, protein, and dietary fibre. All beans contain complex starches that cause flatulence, although cooking methods and ingredients such as Epazote (a Meso-American herb) and Kombu (a type of seaweed) can be added to bean dishes to reduce this effect. People who regularly eat green or dried beans suffer less from flatulence as the microbes in their digestive tracts adjust over time.
Many dry bean varieties contain a toxic chemical called phytohaemagglutinin that can cause nausea, vomiting, and diarrhea. Boiling dried beans for ten minutes will break down the toxin without fully cooking the beans, but cooking at temperatures below 100°C (212°F) is not recommended. Slow cookers can actually make the toxic effect of dry beans greater.
It should be said, though, that because of their storage potential and general productivity, combined with their remarkable nutrition, drying beans are a staple crop for sustainability and self-sufficiency. Bush and pole beans can be eaten fresh, frozen, canned, or pickled. Beans (like peas and lettuces) are also extremely self-fruitful, meaning that they have a genetic tendency to breed true to their parents. This is why all beans (and peas, and lettuces) are open pollinated. And that means that you can save the seeds from your homegrown beans and always have some on hand for the following year. What could be more sustainable than that?