Are all beans legumes? Are all legumes beans? Is there a difference? if so, can you give me an example of a legume that is not a bean, or a bean that is not a legume? (Whichever way that works! :rolleyes:) Thanks!
Many common foodstuffs from legumes are various kinds of beans, but a legume is a member of family Fabaceae, which functions in part by fixing nitrogen in the soil via commensal bacteria in the roots. This allows them to grow in nitrogen-deficient soils.
Common legumes other than beans include peas, peanuts (ground nuts), alfalfa, clover, vetch, lentils, and lupins.
All b eans are legumes, but not all legumes are beans, to answer your question more directly.
Nope, there are a great many beans that are not legumes, including the castor bean, vanilla bean, coffee bean, jumping bean and red bean to name some of the more common ones.
Ancestrally, yes. Today however many legumes no longer have this ability to fix nitrogen.
So to answer the OP:
No, bean is just a name given to plants with certain types of fruit. Most beans are legumes, but by no means all.
No, acacia trees, alfalfa, clover and peanuts and all legumes for example.
Yes, a legume is any member of the plant family/superfamily leguminoseae. They can be trees, vines, shrubs, groundcovers, pondweeds and almost any other form that a plant can take. Legume has an objective, specific meaning.
A bean is nothing more than a type of fruit. It is usually round and hard, but it may refer to a long thin pod as well. As a result a great many totally unrelated plants are described as producing beans.
See above.
Most of those are not surprising, but red bean? What kind of red bean are we talking? Like red beans and rice red beans? Those are legumes, aren’t they?
OK, that’s a red bean I’ve never heard of.
Alfalfa and clover are legumes? I never would have guessed.
Also, coffee beans are not beans. They’re cherries.
They’re both or neither together, depending on how strict you want to be with the terms ‘bean’ and ‘cherry’.
Nope they are beans. Bean isn’t a botanical term, it’s an English word. As such a bean is anything commonly referred to as a bean. Since coffee beans have been called beans for several centuries they are properly beans.
Unless you also commonly refer to people as fish, there is no justification at all in saying that coffee beans aren’t beans.
For laughs, I googled “not a true bean” and found sites stating that things like the Castor Bean is not a true bean - on the grounds that it’s in the Euphorbia family. However, I also found sites stating that the Broad (Fava) Bean is not a true bean - on the grounds that it’s a vetch - except of course it is still a legume, and is classically bean-shaped.
So yeah, ‘bean’ is just a descriptive term for things that resemble beans (and ‘cherry’ is similar)
Yes, terms like “true bean” and “true fish” very rarely clarify anything, since they are just as subject to interpretation as the word they are clarifying. At best they serve to tell the reader that the classification is complex.
There’s a good reason why botanists use actual taxonomic categories to describe things.
I think that’s just a problem with language in general - even for words that do have really precise meanings in a technical/academic field, there’s nothing to prevent people coining completely (or worse, just slightly) different meanings for the same words, in an everyday context.
‘Organic’ in chemistry being the example that springs readily to mind. I can’t think of any taxonomic terms that have been similarly treated, but it wouldn’t surprise me if there are some out there.
Funny - I was going to start a similar thread to ask the following question:
My wife has unpleasant reactions (akin to food poisoning) from some beans but not all legumes.
The known bads:
pinto beans or possibly navy beans: she was forced to eat them as a kid but wouldn’t know exactly what she was eating.
*something in indian cuisine * - my guess is chickpea, since it’s prevalent in that style of cooking.
known goods:
peanuts
green beans
She’s interesting in experimenting with the legume family, mostly to set a good example for our daughter.
Any advice on where the taxonomic lines exist within legumes and which ones are more and less similar to those I’ve listed? Specifically, how about lentils?
I know experimentation is the only way to really find out: fortunately this is not a true allergy so we’re not risking anaphylaxis. She experiences that with seafood.
Well, Pinto beans, Navy beans and French green beans are all varieties of the same species (albeit that green beans are the immature pods)
Huh - I missed that wiki page 
Thanks! I figured that green beans were closer to peas, though in retrospect that’s a silly comparison. Makes this question a lot tougher then.
While green beans are the immature pods of beans, they’re not the same subspecies (? is that taxonomicaly correct ?). Can anyone hazard a guess as to whether the subspecies or maturity is more likely to be responsible for an intolerance?
Varieties of the common bean, Phaseolus vulgaris, can also be referred to as “red beans”, as this Wiki page makes clear:
I think Wikipedia needs a bit of tidying up here, possibly with a disambiguation page for “Red bean”.
The differences are really quite minor - although there are varieties that are selected especially for growing as green beans and others that are selected for their dried mature beans, they’re really not all that different - and any of the varieties can be used for either (I’m going to be growing pinto, cannellini and black turtle beans for both green and dried beans in my garden this year).
It’s possible that the mature dried beans contain compounds that aren’t abundant in the immature pods though.
Thanks Mangetout! Good luck with your crop!