Identification of Flowers: Count Parts, Read the Cluster

To identify a flower, count its parts before you trust its color. NC State Extension's gardener handbook names the four parts to look for: sepals, the small, usually green, leaf-like structures at the base; petals, usually the colored part; stamens, the male organs; and the pistil in the center. A flower with all four is complete; one missing any part is incomplete.

The count is more useful than it looks. NC State gives monocots flower parts in multiples of three and dicots in multiples of four or five. A flower with three or six petals is therefore probably a monocot; four or five points to a dicot.

Color is the least reliable clue, because it shifts with soil, light and age. Note it, but decide with structure. Our guide how to identify a plant explains why the leaf and stem matter as much as the bloom.

Many "flowers" are clusters. NC State Extension calls the arrangement of flowers on a stem the inflorescence, and the common types are easy to tell apart:

• Raceme — an elongated axis with stalked flowers
• Spike — an elongated axis with stalkless flowers
• Umbel — flower stalks that all arise from one point, like the ribs of an umbrella
• Head — all flowers attached to one disk, as in a sunflower

A sunflower or daisy is a head of many small flowers, so counting its "petals" tells you less than you would think. An umbel matters for a different reason: Penn State Extension describes poison hemlock, which resembles carrot and parsley, as having flowers clustered in an umbrella-like grouping, and says every part of that plant is toxic to people and animals.

Where and when you found a flower removes most of the candidates. Wildflower Search, a free filtering site, says its location search is the most important of all its filters. It also filters by elevation within 500 feet, by the week the plant was in bloom, by habitat (alpine, desert, forest, wetland, riparian and others), and by flower traits: number of petals from none to six or many, pea-shaped or irregular flowers, color, and size up to "over 4 inches".

The same site filters on leaf arrangement: alternate, opposite, basal or whorled. Leaves stay on the plant longer than flowers, so record them even when the flower is the reason you stopped.

Pl@ntNet, a citizen-science identification platform run by the French research institutes CIRAD, INRAE, Inria and IRD, asks users to zoom in on different parts of the plant with several photos and to focus carefully, and it rejects images that are too blurry, too cluttered or lacking in information. Its documentation says the app can identify nearly 60,000 species worldwide.

A shot list that works in any app, NatureLens included:

• The flower straight on, filling the frame, so the parts can be counted
• The flower from the side, to show sepals and the flower stalk
• The whole cluster, so the inflorescence type is visible
• A leaf and the stem where it joins, for arrangement and shape
• The whole plant, to show how it grows

Avoid shooting into the sun, which turns petals into a silhouette.

Identification is for learning the plant, not for deciding whether to eat it, brew it or rub it on skin. Several toxic plants have attractive flowers and close look-alikes; see avoiding toxic look-alikes.

If a child or pet has swallowed part of a plant, call Poison Control at 1-800-222-1222 in the US or use the webPOISONCONTROL online tool. Poison Control's first-aid guidance is not to induce vomiting. Take the plant, or a photo of it, with you to the phone.