Identify a Houseplant by Its Leaves: A Key to the Common Ones

To identify a houseplant by its leaves, start with the growth form rather than the color or the pattern. Whether the leaves climb, stand up stiffly from the soil, radiate from a central point, or grow from a woody stem narrows a room full of plants down to two or three candidates before you look at anything else.

This key covers the plants most likely to be in an apartment rather than every houseplant that exists, and the descriptions are quoted from the NC State Extension Gardener Plant Toolbox entry for each species so you can check them against your own plant.

Start here: what shape is the whole plant?

Two entries need qualifying rather than being read straight off the table, and they are covered below.

Pothos and heartleaf philodendron: check the leaf stalk

These two are the most commonly confused plants in this list, and for good reason: both trail, both climb, both have glossy heart-shaped leaves, and both are sold in the same hanging pots. Color and variegation will not settle it, because both come in plain green and variegated forms.

The leaf stalk does settle it, and NC State states it for each. For pothos: Petioles are grooved, described more fully as Petioles slender, shorter than leaf blade, and grooved to clasp the stem. For heartleaf philodendron: Petioles are entire, not grooved.

Run a fingertip along the stalk between the vine and the leaf. A channel running down its length means pothos. A smooth round stalk means philodendron.

The undersides give a second opinion. NC State describes pothos leaves as glossy medium green variegated with paler green underside, and heartleaf philodendron as glossy green above and green or red-purple below. A distinctly purple-red underside points to philodendron, though a plain green underside does not rule it out.

About the calathea row

The quoted description belongs to one species, the peacock calathea (Goeppertia makoyana, formerly Calathea makoyana), and it is precise about that plant: The leaves are large, up to 12 inches long with a pale green to creamy background and a dark green feathered effect from the middle of the leaf to the outer edges.

Calathea and its relatives are a large group with wildly different markings: stripes, spots, pink midribs, deep purple undersides. A plant with an ornate two-tone leaf pattern and a purple underside is likely in this group, but the quoted trait identifies one member of it rather than the whole family. What they share in care terms, and why the brown edges are the thing everyone asks about, is in calathea brown edges.

If your plant is not on this list

The list stops at plants this site has looked into, which leaves a great many out. What transfers is the vocabulary, because it is what the plant databases index on.

When you search, describe the plant in these terms rather than by color alone:

• Growth form. Trailing, upright, clumping from the base, single woody stem, or fronds from multiple canes.
• Leaf arrangement. One leaf per point on the stem, pairs opposite each other, or a rosette with everything emerging from the middle.
• Leaf type. One continuous blade, or a leaf divided into separate leaflets. Divided leaves are worth counting: seven to nine leaflets from one point is a different plant from twenty-five along a stalk.
• Leaf shape. Heart-shaped, sword-shaped, oval, strap-like, or round.
• The underside. Frequently a different color from the top, and frequently the deciding trait.
• Texture. Thin and papery, glossy and leathery, or thick and water-filled.

"Trailing vine, single heart-shaped leaves, purple underside, thin texture" will get you somewhere. "Green plant with pointy leaves" will not.

Identifying it is only half of a safety question

Ten of the thirteen plants above are listed as toxic to cats and dogs, and three are not.

The toxicity column comes from the ASPCA's toxic and non-toxic plants database, checked species by species on 2026-09-08, because that database is written for exactly this question. Every entry is one search away if you want to confirm it:

The thirteenth is the ZZ plant, and it is the one exception: the ASPCA database has no entry for it. NC State's own toolbox entry tags it as a problem for cats and dogs, which is where its Yes in the table comes from, and it is worth knowing that the two sources are not saying the same thing with the same authority on that one row.

One distinction worth carrying, because it caused an error on this page before it was corrected: the NC State species pages also carry a "Poison Severity" rating, and that rating is a general one rather than a cat-and-dog one. The areca palm is the case where the two diverge, listed as non-toxic to pets while carrying a low general severity for the part of it people occasionally eat. Both are true about different questions, and this column answers only the pet one.

If the reason you are identifying a plant is that a pet or a child has chewed on it, call a veterinarian or a poison control line rather than working through a table. Identification helps them, but it is not the first call.

For the non-urgent version of the question, which plants are safe to keep in the first place and how the common ones sort by the chemical they contain, is in houseplants toxic to cats and dogs. The pattern worth knowing in advance: the aroids in this list produce immediate mouth and throat irritation, while the dracaenas produce a different picture, and severity ratings describe the typical case rather than a guarantee.

Common questions

How can I identify a plant without an app? Work from growth form first, then one distinguishing trait. Whether the plant trails, stands up stiffly, clumps from the base or grows on a woody stem eliminates most candidates before leaf details matter, and the remaining pairs usually separate on a single feature such as whether the leaf stalk is grooved.

How do you tell pothos from philodendron? By the leaf stalk. NC State describes pothos petioles as grooved and heartleaf philodendron petioles as entire and not grooved. Leaf shape, gloss and variegation do not separate them reliably.

What is the plant with holes in its leaves? Almost certainly a monstera. NC State describes the leaves as perforated with several holes throughout the blade, and notes that only mature leaves have them, which is why a young plant of the same species has plain leaves.

What plant has stiff upright leaves like swords? A snake plant, described by NC State as stiff, upright, succulent leaves growing in rosettes or clusters, often with transverse banding across the blade.

Is this plant toxic to cats? Depends which one it is, and most of the common ones are. Of the thirteen here, the ASPCA lists ten as toxic to cats and dogs and three as non-toxic: spider plant, calathea and areca palm. The ZZ plant is not in the ASPCA database at all, and its entry here rests on NC State's toolbox instead.

One thing worth doing while you have the plant in front of you

Turn a leaf over.

The underside carries more identifying information than the top does, and almost nobody looks at it: color that differs from the upper surface, the pattern of the veins, and how the stalk meets the blade. It is also the side pests occupy, so the same thirty seconds answers a second question you had not asked yet.