Allamanda blanchetii aka Purple Allamanda

Allamanda blanchetii comes from northeastern Brazil. Its common name is purple allamanda. It belongs to Apocynaceae, the dogbane family. This evergreen shrub has weak stems that climb. Wild plants grow in mangrove swamps and along lowland rivers. Kew places it in a tropical region with dry seasons. Gardens grow it for its leaves and bright flowers.

One source lists a height of about 6.6 feet [2 metres]. Plants can reach 9.8 feet [3 metres], though most stay smaller. Their support affects both height and spread in gardens. Weak stems spread outward and may need pruning for shape. Several stems often grow together at the base. Young stems are green. The bark adds little to the view. Light green leaves feel hairy and grow in whorls, or rings. Each simple, oval leaf has a smooth edge. Leaves measure about 0.33–0.67 feet [0.10–0.20 metres] long. They stay green and do not change colour in fall.

The flowers have a funnel shape. They bloom all year where the climate suits them. Blooms reach about 0.25 feet [0.08 metres] long. They start reddish-purple, then fade to pink with age. This gives the flowers a mix of tones. Sources also list lavender and purple flower colours. The fruit forms a spiny capsule with a hard shell. Green capsules turn brown as they dry and mature. Each measures about 0.08–0.25 feet [0.03–0.08 metres] long. The fruit adds little to the garden display.

Full sun gives the best growth and most blooms. Plants also grow in part shade. Choose a sheltered spot free from frost. The listed USDA range runs from zone 9b through 11b. Rich soil should hold water but let excess water drain. The plant accepts sand, loam, clay, and brief wet spells. It grows in acid to slightly alkaline soil. It copes with little salt. Water well while plants take root in their new spot. Once settled, they can cope with some drought. Pinch new shoots when no buds show to keep growth dense. Hard pruning cuts blooms, which form on new growth.

Train stems over a trellis, fence, arbor, or pole. They can trail over walls or grow as ground cover. Pots and large hanging baskets suit their spreading form. Pruning can shape a plant into a free-standing shrub. Scale, mites, and nematodes may cause trouble at times. Reports do not flag major diseases as a concern. Florida's extension service does not list it as invasive. No one knows of edible uses; every part is poisonous. Sap can irritate skin. Eating plant parts can cause purging. Keep children and pets from eating it. Traditional medicine uses the latex. It can cause vomiting and poisoning.