What is Oxalis triangularis 'Fanny'?

Oxalis triangularis ssp. papilionacea 'Fanny' (also spelled 'Fany') is a tuberous perennial belonging to the family Oxalidaceae. It is native to the wetlands of South America — Brazil, Paraguay, Bolivia and Argentina — where it covers riverbanks and marshes. Its genus name Oxalis comes from the Greek oxus ("acid") — referring to the lemony-acidic flavour of its leaves, due to oxalic acid content.

'Fanny' is the green form of the subspecies papilionacea, characterised by leaflets noticeably larger than those of ssp. triangularis (up to 7 cm wide) — giving it a particularly generous, architectural, graphic appearance. It differs markedly from the purple form ('Atropurpurea'), the most common in commerce, through its entirely glossy green foliage with pearlescent markings and its tender pink flowers. Its English nicknames — Brazilian Butterfly and Love Plant — evoke the butterfly shape of its leaflets and its undeniable charm.

What are the unique characteristics of Oxalis triangularis 'Fanny'?

• Very large triangular dark green glossy leaflets: the primary characteristic of 'Fanny'. The leaflets of ssp. papilionacea are the largest in the genus — up to 7 cm wide — triangular with the tip pointing downward, of a deep, glossy, lustrous green. Each trifoliate leaf is carried on a long fine white-green petiole and forms an ensemble irresistibly evoking a giant shamrock.
• Silvery pearlescent crescent marks: at the centre of each leaflet, subtle silvery pearlescent crescent-shaped markings create a refined natural pattern. These marks are characteristic of 'Fanny' and distinguish it from the plain green form.
• Abundant pale pink flowering: from spring to autumn, long slender flowering stems rise above the foliage bearing small umbels of 5-petalled pale pink to pale lilac flowers with a luminous yellow-green centre. Flowering is generous and continuous over several months.
• Fascinating nyctinasty — the plant that sleeps: the most captivating botanical phenomenon of the triangular oxalis. Each evening, the leaflets fold downward and close, reopening each morning in the light — a slow but clearly perceptible movement. The same phenomenon occurs during heavy rain or prolonged drought. When handled, the plant may also partially fold in response to touch.
• Edible plant with lemony-acidic flavour: the leaves, flowers and tubers of Oxalis triangularis are edible, with a pleasant lemony, acidic flavour — perfect for dressing a salad or garnishing a plate. The pale pink flowers make a beautiful edible decoration. Note: consumption should remain moderate due to oxalic acid content (can cause calcium deficiency in excess). Toxic to cats, dogs and other pets.
• Tuberous rhizomatous perennial: the oxalis develops from scaly tuberous roots (pseudo-bulbs), which allow it to survive dormancy periods and re-sprout vigorously each spring. They multiply naturally and are easily divisible for propagation.
• Spreading, ground-covering habit, 20–35 cm high × 40–50 cm wide: the plant forms a broad, dense, compact clump with no aerial stem — all leaves emerge directly from the rhizomes. Its spreading, tapestry habit makes it an excellent ground-cover in dappled shade.

Oxalis triangularis 'Fanny' vs 'Atropurpurea': what are the differences?

• 'Fanny' (this form): dark glossy green foliage with pearlescent markings, very large leaflets (up to 7 cm), pale pink to pale lilac flowers. Slightly hardier than the purple form.
• 'Atropurpurea' (purple form): deep purple foliage marbled with pink, most widely available in commerce, white-pink flowers. More dramatic as a decorative indoor plant.
• Both forms share the same cultivation requirements and the same fascinating nyctinastic behaviour.

How to grow Oxalis triangularis 'Fanny'?

• Light: bright light without direct sun. 'Fanny' needs abundant brightness to flower generously, but fears midday direct sun which scorches the leaflets. Indoors, an east- or west-facing windowsill is ideal, or behind a sheer curtain. Outdoors, prefer dappled shade or fresh partial shade.
• Soil: draining, humus-rich, fresh, neutral to slightly acidic. Recommended pot formula: 2/3 indoor plant compost and 1/3 perlite or sand. Place a draining layer (clay pebbles) in the bottom of the pot. Pot must have drainage holes.
• Planting the tubers: plant pseudo-bulbs 5 cm deep, spaced 5 to 8 cm apart, or 5 tubers in a 20 cm diameter pot. In open ground, plant in April after the last frosts.
• Watering: regular but moderate — allow the substrate to dry slightly at the surface between waterings. The oxalis fears waterlogged substrate far more than occasional missed waterings. Use non-calcareous water at room temperature. If the plant loses its leaves from prolonged drought, it has simply entered dormancy — it will re-sprout when watering resumes.
• Temperature: ideally 15 to 25°C. Fears excessive heat (above 27°C it may enter summer dormancy). Hardy to -5 to -6°C in well-drained soil for the green varieties.
• Feeding: apply a flowering plant fertiliser every 2 weeks during the growth period (spring-summer). Stop all feeding once the foliage begins to yellow, signalling dormancy entry.

What are the care requirements?

• Winter dormancy: in November, cut back the faded foliage. Move pots to a cool, dark location (5–12°C — a cellar or garage works well), stopping all watering. Bring out in February and repot if necessary. In open ground in mild regions, leave in place with a light protective mulch.
• Summer dormancy: if the plant loses its leaves in summer (excessive heat or drought), reduce watering and simply wait — it will re-sprout when conditions improve.
• Repotting: annually in spring in a slightly larger pot. This is also the right moment to divide the tubers for propagation.
• Deadheading: regularly remove spent flower stems to stimulate new bud production.

Where to grow Oxalis triangularis 'Fanny'?

• As an indoor plant: very bright east- or west-facing windowsill, luminous shelf, desk or side table — its graphic foliage and nyctinasty make it a living spectacle observed with daily fascination.
• In a hanging basket: the long flower stems and spreading habit suit hanging culture near a bright window very well.
• On a terrace or balcony: from May to September, in partial or filtered shade. It appreciates the outdoor freshness in summer (avoid full sun).
• As a ground-cover in dappled shade: in mild-winter regions, it can be used as a tapestry ground-cover under shrubs or as a shaded border edging. Find our other botanical collection curiosities.
• In the kitchen and as edible decoration: a few leaves or pale pink flowers in a salad bring an original acidic note and a beautiful decorative touch.

What are the advantages for collectors?

• The largest-leaved green form of the genus: the leaflets of ssp. papilionacea 'Fanny' are among the largest available in cultivation — a remarkable architectural character compared to more compact forms.
• Nyctinasty as a daily spectacle: few indoor plants offer such visible, regular plant movement — the leaflets folding each evening and deploying each morning fascinate adults and children alike.
• Triple ornamental, botanical and culinary interest: decorative through its foliage and flowers, fascinating through its nyctinasty, and edible — a multi-faceted plant unique in any collection.
• Very easy and extremely tolerant: it forgives missed waterings (it simply enters dormancy), requires minimal care, and offers longevity of several years or even decades when well tended.

How to propagate Oxalis triangularis 'Fanny'?

• By tuber division: in February, at spring repotting time. Gently remove the plant from its pot and separate the pseudo-bulbs, keeping at least 2 to 3 rhizomes per section. Replant immediately in fresh draining substrate.
• No seed propagation: Oxalis triangularis generally produces no seeds (it is not self-fertile — commercially sold bulbs being all vegetatively propagated and genetically identical). Tuber division is the only practical propagation method.