Identify a flower from a photo

Flowers are the part of a plant that botanists rely on most, because they vary less within a species than leaves do and differ more between species. That also makes them the best photo you can give an identifier. The hard cases are garden flowers bred into shapes and colours the wild plant never had, and the many small flowers that look alike at a glance. For those, a few simple checks of your own go a long way.

How to photograph a flower

• Fill the frame with one fully open, fresh flower, in focus, from the front.
• Take a second photo from the side, showing the flower stalk and the green sepals underneath the petals.
• If the flowers are small and grouped, as in a daisy head or a flat-topped cluster, photograph the whole group as well as a single flower.
• Add a photo of a leaf. Many look-alike flowers are easier to separate by their leaves.
• Avoid wilted or half-open flowers: shape and colour change as a flower ages.

Light matters: open shade or an overcast sky shows colour and detail best, and harsh sun bleaches pale petals. More on framing is on the plant identifier page.

What to check in the flower

Count the parts

Count the petals, or the lobes if the petals are joined. Monocots, such as lilies, irises, onions and orchids, usually have their flower parts in threes or multiples of three. Most other flowering plants have them in fours or fives. In lilies and tulips the three petals and three sepals look alike, so the flower appears to have six petals.

Symmetry

A radially symmetric flower looks the same from any side, like a buttercup, a rose or a tulip. A bilaterally symmetric flower can only be split into mirror halves one way, like a pea, a snapdragon, a violet, a sage or an orchid. This one feature splits flowers into two large groups before you look at anything else.

Separate or joined petals

Petals can be separate, each one able to fall on its own (rose, buttercup, poppy), or joined into a tube, bell or trumpet (morning glory, bellflower, foxglove).

One flower or many?

• A daisy, sunflower or dandelion is not one flower but a head of many tiny flowers packed together. That arrangement marks the daisy family, one of the largest plant families.
• An umbel is a cluster of small flowers on stalks that spread from one point, like the ribs of an umbrella. It is typical of the carrot family (dill, fennel, Queen Anne's lace) and is also found in onions and their relatives.
• A spike or a raceme carries flowers along an upright stem, as in lavender, foxglove and snapdragon.

The stem and leaves

A square stem with leaves in opposite pairs, often aromatic when rubbed, points to the mint family: mint, basil, sage, lavender and many others. Milky sap from a broken stem is found in a limited number of plant families, including spurges, dandelions and lettuces, milkweeds, figs and some poppies. Spurge sap irritates skin and eyes, so wash it off if you get it on your hands.

Garden flowers versus wild flowers

• Double flowers, with extra rows of petals, are bred forms of roses, peonies, camellias and many others. The identifier can often still name the genus, but the extra petals hide the features of the wild species.
• Many popular garden flowers are hybrids of several species, so an answer at the genus level, such as Rosa or Petunia, is the realistic best.
• Colour is the least reliable feature. One species can come in many colours, and the flowers of many bigleaf hydrangeas are blue in acidic soil and pink in alkaline soil.

Look-alikes to be careful with

• White daisies: chamomile, scentless mayweed, oxeye daisy and feverfew all have white petals around a yellow centre. Their leaves separate them better than the flowers: finely divided and feathery in chamomile and mayweed, toothed or lobed in oxeye daisy and feverfew. German chamomile smells sweet, and its cone-shaped centre is hollow when cut lengthwise.
• White umbels: Queen Anne's lace (wild carrot) has hairy stems and sometimes, but not always, one dark purple flower in the middle of the umbel, so do not rely on that flower alone. Poison hemlock, which is deadly, has smooth, hairless stems with purple blotches. Do not handle or taste a white umbel you have not identified with certainty.
• Lilies: true lilies and daylilies look different from each other but are both dangerous to cats, and so are their leaves, stems and pollen. Plants called lilies that are not, such as peace lilies and calla lilies, are toxic in a different, usually milder way.

Flowers on fruit plants

Flowers matter for growers too, since they tell you a plant is about to fruit. Some are unmistakable once you have seen them: the elaborate, fringed flowers of passion fruit, the crimson powder-puff flowers of Malay apple, and the small flowers that grow straight out of the trunk of cacao and jaboticaba. For trees that are not in flower, see the fruit tree identifier.