Passiflora ligularis

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Passiflora ligularis, the sweet granadilla, is an evergreen climbing plant in the passionflower family. It grows as a vine up to about 5 meters long, using coiling tendrils to climb over the ground or into nearby vegetation. The leaves are ovate, 8–22 cm long and 6–17 cm wide, dark green on top and green-gray underneath. Younger leaves can have a slight violet tint. The plant has shallow roots.

Flowers are 6–12 cm across, with a green outside and a white inside. Petals are white (sometimes with a hint of pink or violet) and the flowers have a sweet, musky scent. Pollination is mainly done by bumblebees, honeybees, and large wasps, though strong winds can interfere. Each flower lasts only one day, and pollen viability can vary with the time of day. The plant can flower year-round if light is not limiting; if daily sunshine falls below about 8 hours, the fruit can turn brown.

The fruit is green when unripe and becomes yellowish orange with small white dots when ripe. It is about 6.5–8 cm long and 5.1–7 cm wide, with a hard shell and a soft, sweet, aromatic pulp inside. There are about 250–300 seeds per fruit; seeds are black and surrounded by a gelatinous pulp. The pulp is edible and rich in vitamins A, C, and K, plus phosphorus, iron, and calcium.

Growing conditions and care
- Soil: well-drained soils from loam to clay, amended with peat and sand to improve aeration. Prefers lightly acidic to neutral pH (about 6–7). It grows best in soils rich in organic matter.
- Climate: warm, humid environments. Optimal temperatures are 15–25°C, with 1000–2000 mm of rainfall per year. Plenty of sunlight boosts growth and fruit sweetness.
- Planting: seedbed should be well-drained and nutrient-rich. Sow seeds 1–2 cm deep, with adequate spacing. Keep soil consistently moist but not waterlogged. Germination typically occurs in about 15 days at 20–30°C.
- Growth and care: use trellises or other supports for the vine. Prune regularly to remove dead or diseased growth and to improve air flow and fruit production. Apply balanced N-P-K fertilizer every 4–6 weeks, adjusting for soil tests and plant needs.
- Growth stages: germination, rapid vegetative growth of climbing stems and lobed leaves, flowering about six months after planting (pollination by bees or wasps), and fruit ripening about 70 days after pollination. The plant tolerates moderate salt but high salinity can slow growth.

Pests, diseases, and management
The plant can be affected by pests such as leaf-feeding insects and rodents that eat seeds. Fungal diseases like anthracnose (Colletotrichum) and collar rot (Fusarium solani) can occur, and viral diseases like passion fruit woodiness can reduce yields. Mycorrhizal fungi help nutrient uptake and disease resistance. Integrated pest management and the use of resistant varieties improve control.

Breeding and use
The Passiflora genus contains many species, offering a rich gene pool for breeding. Researchers work on improving tolerance to abiotic stresses (like drought and salinity), fruit quality, disease resistance, and yields.

Native range and importance
Passiflora ligularis is native to Central and northwestern South America and has been introduced to regions including India, parts of East and Southeast Asia, New Zealand, Australia, and some Pacific islands. It is considered invasive in places such as Haiti, Jamaica, Indonesia, the Galápagos Islands, and Samoa; New Caledonia restricts its introduction due to weed risk. In some areas, it can affect native vegetation and ecosystems and may pose risks to livestock.