Why Plants Die
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Purple shamrock

Oxalis triangularis, Oxalidaceae

Sources last read 14 September 2026.

Middling It gives warning, with time to act.

Also called False Shamrock, Love Plant and Purple Wood Sorrel.

Purple shamrock (Oxalis triangularis), the whole plant.
Naimcbim Woadd, CC BY-SA 4.0 · Wikimedia Commons

Purple shamrock is toxic

  • Toxic to cats. Toxic principle: Soluble calcium oxylates. Clinical signs: All parts of the plant have toxic potential, although the possibility of serious effects is usually limited to ingestions of large quantities. Consuming Oxalis species can produce colic in horses…. ASPCA ASPCA names the genus (Oxalis spp.), not the species.
  • Toxic to dogs. Toxic principle: Soluble calcium oxylates. Clinical signs: All parts of the plant have toxic potential, although the possibility of serious effects is usually limited to ingestions of large quantities. Consuming Oxalis species can produce colic in horses…. ASPCA ASPCA names the genus (Oxalis spp.), not the species.
  • Not assessed for people. RHS publishes no harm statement for this plant. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.

What the sources say about its care

Sources file this plant under other names: Oxalis spp (ASPCA, genus only). Citations below point at the name its source uses.

Light
Partial shade
RHS · read 13 September 2026
Water
Moist but well-drained
RHS · read 13 September 2026
Humidity

No source read publishes a humidity figure for any plant on this site. What follows is general guidance for foliage plants.

ASHRAE recommends indoor relative humidity between 30% and 60% 30–60%
Penn State Extension · read 13 September 2026
Temperature

How cold this tolerates, not what it prefers. No source read for this site publishes a preferred range for a plant indoors.

H3 — -5 to 1°C -5 to 1 °C
RHS · read 13 September 2026
Soil
Sand, Loam, Chalk; pH Alkaline or Neutral or Acid
RHS · read 13 September 2026
Toxic to cats
Toxic
ASPCA names the genus (Oxalis spp.), not the species.
ASPCA, filed as Oxalis spp. · read 13 September 2026
Toxic to dogs
Toxic
ASPCA names the genus (Oxalis spp.), not the species.
ASPCA, filed as Oxalis spp. · read 13 September 2026
Harmful to people
No statement of harm to people is published for this plant; that absence is not evidence it is safe.
RHS · read 13 September 2026

How it usually goes wrong

A thin dry rim that crumbles between the fingers

A narrow dry border on the purple shamrock, often with a faint yellow line against the healthy tissue. It appears on several leaves at once rather than spreading from one.

Heated air holds less water than the plant loses into it, so moisture leaves the leaf faster than it arrives. Penn State Extension cites ASHRAE's indoor range of 30% to 60% relative humidity, and winter heating often takes a room below it. That applies while it is grown indoors; its RHS rating of H3 describes a plant that also grows outside, where the air is seldom that dry.

Telling it apart: Whether it crumbles or smears. Crisp is water lost; soft and dark is cold or rot.

Penn State ExtensionPurple shamrock leggy, leaning growth: causes
Leaves bruised and browned along the edges after a gale

The purple shamrock looks battered rather than sick. Leaves are nicked and browned at the edges, and the damage is heaviest on the most exposed side.

Its source describes a sheltered spot. In an exposed one, wind both dries the leaves and damages them physically, which is why the marks follow the direction of the weather.

Telling it apart: Whether it followed stormy weather. Damage that appeared overnight after wind is weather; damage that develops over weeks is something else.

RHSDiagnose brown tips and edges on this Purple shamrock
The crown grows thin and sparse, and leans

The purple shamrock looks sparse rather than sick: fewer leaves, spaced further apart, all angled toward the window.

Its source puts it in partial shade. Under that, each new leaf costs more than it returns, so the plant builds fewer and thinner ones.

Telling it apart: Whether old growth is affected. Light shows in what arrives next; feeding shows in what is already there.

RHSPurple shamrock leggy, leaning growth: causes
Yellowing that begins at the outer leaves

A sour smell from the compost is common on a purple shamrock, and the outer leaves come away when pulled. The surface may look dry while everything beneath it is not.

Its source describes soil that is moist but well-drained. Roots held below that are short of air, and roots short of air stop moving water, so the crown wilts in a wet pot.

Telling it apart: Whether new growth is affected too. Root damage shows up everywhere at once; ordinary leaf loss shows only in the oldest leaves.

RHSPurple shamrock leaves turning yellow: causes

Not sure which it is? Ask the diagnosis questions for Purple shamrock.

Routine care

Watering
Plant in a loamy, well-drained potting mix and let the surface dry between waterings. Water less and wait until new growth shows.
NC State Extension · read 13 September 2026
Propagation
Divide the rhizome, or break off the scale leaves, which grow into new plants.
NC State Extension · read 13 September 2026
Increase from seed or division.
RHS · read 13 September 2026
Pruning
Pruning is not needed.
RHS · read 13 September 2026
Pests and diseases
Outdoors, snails and slugs can attack it. Disease risk: rust diseases.
RHS · read 13 September 2026

Move something and watch

Loading the simulator. It needs JavaScript; the care table above does not.

About the plant

Oxalis triangularis, commonly called false shamrock, is a species of perennial plant in the family Oxalidaceae. It is native to several countries in southern South America. This woodsorrel is typically grown as a houseplant but can be grown outside in USDA climate zones 8a–11, preferably in light shade.

From Wikipedia, CC BY-SA 4.0 · read 13 September 2026

Native range
Peru to Brazil and N. Argentina
World Checklist of Vascular Plants, June 2026 release, CC BY.
Kew WCVP · read 13 September 2026
South America
NC State Extension · read 13 September 2026
Peru to Brazil and N Argentina
RHS · read 13 September 2026
Climate
seasonally dry tropical
World Checklist of Vascular Plants, June 2026 release, CC BY.
Kew WCVP · read 13 September 2026
Growth form
tuberous geophyte
World Checklist of Vascular Plants, June 2026 release, CC BY.
Kew WCVP · read 13 September 2026
Herbaceous Perennial; habit clumping, spreading
NC State Extension · read 13 September 2026
Clump forming (deciduous)
RHS · read 13 September 2026
Size
Height 6–18 in; width 12–24 in
NC State Extension · read 13 September 2026
Height 0.1-0.5 metres; spread 0.1-0.5 metres after 1–2 years
RHS · read 13 September 2026
Flowering
Flowers purple/lavender, white; blooms in fall, summer
NC State Extension · read 13 September 2026
Flowers purple in summer; white in summer
RHS · read 13 September 2026
Uses

What sources record people using this plant for. A traditional or medicinal use listed here is a record of use, not advice to eat it or treat anything with it.

The leaves and flowers can be eaten, in moderation.
NC State Extension · read 13 September 2026

Common problems with Purple shamrock

Other Oxalis

Plants with similar care

Sources

What this does not cover

The figures above are what published sources say, not measurements of the plant in your room. They say nothing about your pot size, your water, the season, or how far from the glass the plant stands, and those decide more than any figure here does.

Humidity has no species figure because no source read for this site publishes one, and the only temperature published for this plant is a cold floor. The simulator fills those gaps with general figures for its kind of plant, marked as general and listed on how we read sources. Where a toxicity row says the plant was not assessed, that is the absence of a finding and not a finding of safety.

If something is already wrong, the diagnosis tool asks about the soil, the window and the watering, which is where the answer usually is.