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A field journal of theHouse&Hedgehome & garden, kept in ink
Entry 118 · bulb

Purple shamrock

Oxalis triangularis · Oxalidaceae
bright indirect lightwater every 6 to 14 dayseasycats toxic · dogs toxic
Add to my plants
In brief
Lightbright indirect light
WaterEvery 6 days in the growing season, every 14 in winter
PetsCats toxic, dogs toxic

Source: ASPCA Animal Poison Control, toxic and non-toxic plants list, shamrock entry for Oxalis species.

Toxic to cats and dogs if chewed. Listed as toxic to cats, dogs and horses. The soluble oxalate salts can affect the kidneys in quantity, though a small nibble usually causes only drooling and an upset stomach. Keep it where an animal that eats houseplants cannot reach it, and speak to a vet if one does. In South Africa telephone the Poison Information Helpline on 0861 555 777; in the US, the ASPCA Animal Poison Control Center on (888) 426-4435.

The purple shamrock comes from South America, where it grows from small scaly bulbs that let it disappear underground when the weather turns against it. Indoors it does the same thing, which is why it is so often thrown away by owners who think they have killed it: after a hot spell, or simply when it feels like it, the whole plant collapses and dies back, and a few weeks of cool dry rest brings it up again. The triangular leaves fold shut at night and open in the morning, driven by the same swollen hinge at the base of each stalk that the prayer plants use. It is not a shamrock and not related to clover, and it is on the ASPCA list as toxic to cats and dogs, which is worth knowing for a plant that sits at table height.

Ailments observed

Leaves falling offDormancy, which is normal, or heat and drought bringing it on early. Cut the old growth off, keep the pot barely moist and cool for a few weeks, then water again and it regrows.
Long bare stems and pale new leavesNot enough light. Move it brighter. Cut the stretched growth away and the new leaves come in short and deeply coloured.
White powder on the leavesPowdery mildew in still crowded growth. Thin the stems, improve the air movement, and water at the base.

Questions from the margin

My purple shamrock has collapsed and looks dead. What now?

It has almost certainly gone dormant, which it does after a hot spell or simply on its own schedule. Cut the old leaves away, keep the pot barely moist somewhere cool for a few weeks, then water normally. New shoots come up from the bulbs.

Filed underPlants that forgive a beginner

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