Both are Pilea. Both have ASPCA non-toxic ratings. Both are compact desktop plants that stay under a foot tall. Beyond that, these two plants have almost nothing in common — different leaf shapes, different native climates, different humidity needs, different origins. If you're picking one based on care requirements rather than looks, the distinction matters.
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Why this comparison matters
Care guides sometimes group all Pilea species together, as though the genus name tells you what the plant needs. It doesn't. Pilea peperomioides (the UFO plant or Chinese money plant) is from the temperate mountain forests of southwestern China — it tolerates drier air and cooler temperatures than most houseplants. Pilea cadierei (the aluminum plant or watermelon pilea) is tropical, originating in China and Vietnam, and wants more humidity to stay happy.
The leaf shapes are so different that you'd never mistake one for the other in person, but online they often appear in the same "Pilea care" articles as if they're interchangeable. They're not. Read the label when you buy, and then treat them according to their actual origins.
What they are (botanically)
Pilea peperomioides Diels belongs to family Urticaceae (the nettle family — though Pilea has no stinging hairs). Per Kew POWO, it is native to China (SW. Sichuan, W. Yunnan) — temperate mountain habitat, not tropical rainforest. It's a perennial or subshrub in that climate zone.
Pilea cadierei Gagnep. & Guillaumin is also Urticaceae. Per Kew POWO, the native range is China (Guizhou, Yunnan) to Vietnam — a subtropical to tropical origin. NC State Plant Toolbox confirms Vietnam as the origin of the species first described under that name.
Both are compact, shrubby plants that stay roughly 6–12 inches tall indoors. The family is also home to Pilea microphylla (artillery plant) and other common houseplant species, but the care profiles within Urticaceae vary considerably by species.
Side-by-side care table
| Need | P. peperomioides (UFO plant) | P. cadierei (Aluminum plant) |
|---|---|---|
| Light | Bright indirect; some direct morning sun tolerated | Bright indirect; avoid full sun — leaves bleach in direct light |
| Water | Moist, well-drained (standard potting mix with added ) potting mix; allow surface to dry slightly | Moderate; reduce in fall and winter; keep evenly moist in growing season |
| Humidity | Tolerates average home humidity — less demanding per its temperate origins | High humidity preferred; poor air circulation in high humidity can cause powdery mildew |
| Temperature | Tolerates cooler conditions consistent with its temperate mountain origin | Standard warm indoor temperatures; more typical tropical houseplant range |
| Soil | Moist, well-drained potting mix | Peaty, well-draining (add perlite for extra drainage) mix |
| Pruning | Propagates by offsets (pups) from the base | Pinch stem tips to maintain compact shape; leggy without pinching |
Pet toxicity
Pilea peperomioides carries a favorable safety profile from multiple sources. NC State Plant Toolbox explicitly notes it is "safe for pets and children." The ASPCA's article on safe plants around pets includes the Chinese money plant as non-toxic (ASPCA — Are Succulents Safe Around Pets?). Additionally, the related species Pilea nummulariifolia (creeping pilea) is explicitly listed as Non-Toxic to Dogs, Non-Toxic to Cats, and Non-Toxic to Horses in the ASPCA Toxic and Non-Toxic Plants database, supporting the genus-level non-toxic profile.
Pilea cadierei has a confirmed ASPCA entry under both "Aluminum Plant" and "Watermelon Pilea" (ASPCA — Aluminum Plant): Non-Toxic to Dogs, Non-Toxic to Cats, Non-Toxic to Horses. The ASPCA lists the scientific name as Pilea cadieri (one 'i'), which is a spelling variant of the same species.
This is one of the rare articles where both plants in the comparison are confirmed non-toxic to cats and dogs per ASPCA. If you have pets and want a desktop or windowsill plant, either of these is a good call from a toxicity standpoint. The care difference — not the toxicity — is what should drive your choice.
How to tell them apart
The leaf shapes are distinctive enough that confusion is unusual once you've seen both:
Pilea peperomioides has orbicular (perfectly round), peltate leaves — meaning the leaf stem attaches to the center of the leaf underside rather than the leaf edge, like a lily pad. NC State describes them as "fleshy, circular, dark green leaves; peltate with long stems attach at the center of the leaf." The leaf margins are smooth (entire). No pattern on the leaf surface — uniform dark glossy green.
Pilea cadierei has elliptic to obovate leaves (elongated oval, widest toward the tip) with a normal base attachment at the petiole. The defining feature is four rows of raised silvery patches along the leaf surface — this metallic sheen is what earned it the name "aluminum plant." Leaf margins are serrate (toothed). The contrast between the dark green base and the silver patches is the species' only visual trick, and it's a good one.
In short: round and solid green = peperomioides. Oval with silver patches = cadierei.
Native climate clue: P. peperomioides comes from the mountains of Sichuan and Yunnan, which have cool winters and moderate summers. It handles a chilly room or a cool windowsill better than most tropical houseplants. P. cadierei is subtropical-tropical and will sulk in a cold draft.
Which one should you get?
Get P. peperomioides (UFO plant) if: You want something genuinely quirky-looking — the round peltate leaves on long stems are visually unique. You have pets. You live in a drier climate or your home humidity is average. You want a plant that propagates easily by producing small pups (offsets) from the base, which you can pot up and give away. This is a low-drama houseplant.
Get P. cadierei (aluminum plant) if: You want interesting leaf texture and metallic patterning. You have a kitchen, bathroom, or other space with higher ambient humidity — it benefits from the moisture. You're willing to pinch stem tips regularly to keep it from going leggy (it needs that more than the UFO plant does). You already have some tropical houseplants and can group them to share humidity.
For absolute beginners: P. peperomioides is easier. It's more tolerant of average home conditions, and NC State calls it "safe for pets and children" — a reassuring baseline. The aluminum plant is slightly more demanding about humidity and needs more active management of its shape.
Common misreports
The most common misreport in Pilea care is treating all species in the genus as interchangeable. The genus Pilea contains over 700 species across wildly different native habitats — from tropical rainforests to high-altitude temperate mountain zones. Care guides that say "Pilea needs high humidity" are probably thinking of P. cadierei (tropical Vietnam origin). Care guides that say "Pilea tolerates average home humidity" are probably thinking of P. peperomioides (temperate mountain China). Both are accurate statements about different plants.
The second misreport involves the "UFO plant" name. Pilea peperomioides became a collector's item in Europe and North America before it was widely available commercially — it spread primarily through cuttings and pup sharing among houseplant enthusiasts. Because it was rare in the nursery trade for a long time, some older care guides describe it as difficult or rare to find. It's now widely available at most garden centers and plant shops. The care isn't difficult; the plant just has specific light and propagation habits worth understanding.
For P. cadierei, the aluminum plant name occasionally causes confusion — some buyers expect something metallic or unusual and are surprised by a compact, shrubby plant with silver leaf patches. The ASPCA's use of both "Aluminum Plant" and "Watermelon Pilea" as names for the same species reflects this common name proliferation. Both names appear in the ASPCA database entry.
Frequently asked
Why do some sources call Pilea cadierei "watermelon pilea"?
Both names refer to the same plant. The "watermelon pilea" name comes from the silver patches on dark green leaves resembling the rind pattern of a watermelon. The ASPCA lists both names in its entry. "Aluminum plant" refers to the metallic sheen of those same silver patches. If you see either name at a nursery, you're getting Pilea cadierei.
Will P. peperomioides stop making pups if I don't give it enough light?
Yes, roughly. The plant produces pups (offsets from the base or from the central stem) more readily in brighter conditions. In low light, growth slows generally and pup production drops. NC State recommends bright indirect sunlight, and some morning direct sun is tolerated. If your UFO plant hasn't made pups in many months, try moving it a few feet closer to a window before troubleshooting anything else.
Can I group P. cadierei with other tropical plants to boost humidity?
Yes — grouping plants together raises local humidity slightly through transpiration. This is a common low-tech solution. For P. cadierei, which NC State notes prefers high humidity, grouping with other moisture-loving plants helps. One caveat from the same NC State source: "in high humidity or poor circulation, powdery mildew can occur." Make sure there's some airflow in the group — don't pack plants into a completely still corner.
Sources: Kew POWO — Pilea peperomioides · Kew POWO — Pilea cadierei · NC State — Pilea peperomioides · NC State — Pilea cadierei · ASPCA — Aluminum Plant · ASPCA — Watermelon Pilea · ASPCA — Creeping Pilea · ASPCA — Are Succulents Safe Around Pets?