It always surprises me how hard some people find it to identify these widely-grown crops, even those who live in the countryside. They are all species of grass bred over thousands of years, and generically known as corn (as in cornfields). Just to add to the confusion, their much bigger cousin maize is also known as corn, especially the sweetcorn we humans eat.
Anyway, this page has some photos that might help you to tell the difference between oats, barley and wheat once they’ve got past the grass-like stage in spring. Farmers don’t grow rye, spelt and other more unusual grains near here, so you will have to resort to searching to find examples if you’re interested.
Wheat
From a distance, wheatfields start off a glaucous blue-green colour before the ears ripen. Most modern wheat has few if any awns (whiskers), and the ears start off and remain more or less upright. Most of the wheat grown here in Uplyme is beardless (it has no awns or bristles), but this year for the first time, the field next door is a mixture of the usual type (seen bottom left) with drifts of bearded wheat (seen bottom right).
Barley
This has to be my favourite crop. It starts off a lovely lime green colour that shimmers in the breeze as the long shining awns shiver and sway, before slowly turning gold when the ears ripen and turn down. If you see a field that looks like green velvet, it’s probably unripe barley. Most of what’s grown here has 4 rows of grain in the flattened ears, but once, I found a field of a 6-row variety that was very fulsome.
Oats
These are the easiest to identify, with airy inflorescences of dangling awned grains. I always think of them as being the biggest of the three – commonly growing to my head height, but this year, the field next door is full of a very dwarf variety barely 50cm tall. Unripe oat fields start off a soft pale green, then turn gold, but usually retaining a characteristic green stripe along the tractor marks.
Straw
A by-product of the grain, used for animal feed and bedding. Barley straw is very prickly, as my memory of childhood games in a barn full of the stuff will attest, but happily eaten by equines, as is oat straw. Wheat straw is less palatable but much easier on the skin. Wheat straw (called wheat reed, though it isn’t) was commonly used to roof cottages hereabouts, but modern varieties are too short and the local thatchers grow long-stemmed varieties that are gathered into stooks in the old-fashioned way, rather than combined and baled from windrows.
(Photos of windrows and bales are harder and harder to come by. When we first lived here, there were several days from combining when I could find interesting patterns in the aftermath, but now the trend is to cut, bale and cart away all in one day.)