Heliotropium curassavicum (alkali heliotrope)

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Heliotropium, Genus, curassavicum, Species,

Genus & species

alkali heliotrope

Boraginaceae Americas

Attracts Pollinators Attracts Butterflies Deer Resistant Drought Tolerant

SunFull Sun

WaterLow · drought-tolerant

HardinessZones 8–11

Overview

Heliotropium curassavicum is a low, sprawling perennial herb, sometimes behaving as an annual, with smooth, fleshy, blue-green stems and leaves that spread 8-24 in (20-60 cm) across and rise only 4-16 in (10-40 cm) high. The hairless, somewhat succulent leaves are 0.4-2.4 in (1-6 cm) long, narrow, and spoon- to lance-shaped, with a waxy grey-green bloom. From spring through autumn the plant produces coiled flower clusters that unroll as they bloom, each carrying small white to pale-blue flowers about 0.2 in (4-5 mm) wide with a yellow throat that ages darker. It spreads by creeping roots as well as seed and forms patches on saline, alkaline, and disturbed ground. The foliage contains pyrrolizidine alkaloids that are toxic to livestock and people if eaten. It tolerates salt, drought, and periodic flooding, and grows along shorelines, salt flats, roadsides, and irrigated land across the Americas and, as an introduction, in many warm regions worldwide. Plants die back in cold winters and regrow from the rootstock.

Native Range

Native to the Americas, from the United States through Mexico, Central America, the Caribbean, and South America, on saline and alkaline soils. It has naturalised as a weed in Australia, southern Europe, Africa, and Asia.

Suggested Uses

Rarely grown as an ornamental and most often managed as a weed of saline and disturbed ground. It has localised use for stabilising salty or alkaline soils and has featured in traditional medicine within its native range.

How to Identify

Recognised by sprawling, hairless, fleshy blue-green stems and narrow, waxy, grey-green leaves that are smooth rather than hairy, unlike most heliotropes. The small white flowers grow in paired, coiled clusters that uncurl as the flowers open. The yellow throat of each flower fades to purple with age.

Appearance

Size & Dimensions

Height4" - 1'4"

Width/Spread8" - 2'

Colors

Flower Colors

white

blue

Foliage Colors

green

Bloom Information

Bloom Period

~20 weeks

Flowers: April–September

Spring Summer Fall

Flowering extends over a long season from spring through autumn wherever conditions stay warm and moist. The coiled flower clusters unroll gradually, opening a few small flowers at a time over several weeks. In hot inland sites flowering peaks after rainfall or irrigation.

Detailed Descriptions

Foliage Description

grey-green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.5 - 9.0 (Neutral to alkaline)

3579

Soil Types

sand clay loam

Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

tender

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Heliotropium curassavicum grows in full sun on sandy, saline, and alkaline soils, including poor and compacted ground that few other plants tolerate. It withstands drought, salt spray, and short periods of flooding once established. The plant spreads by deep, creeping roots, so it persists and regrows after the top growth is removed. It needs no feeding or irrigation in suitable climates and is generally treated as a weed rather than cultivated. In cold-winter areas the foliage dies back and resprouts from the roots in spring.

Pruning

No pruning is required. Spreading growth can be cut or pulled to limit its extent, though deep roots regenerate readily and complete removal is difficult. Cutting before seed set reduces spread by seed.