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Hexasepalum teres

rough buttonweed

Rubiaceae

Central, southern, and eastern United States

Attracts Pollinators Drought Tolerant

Native to North America

SunFull Sun

WaterLow · drought-tolerant

Overview

Hexasepalum teres, formerly known as Diodia teres, is a low summer annual in the madder family (Rubiaceae), with wiry, branching stems 4-24 inches (10-60 cm) long that sprawl or rise from a taproot. The narrow, stiff, opposite leaves are 0.4-1.5 inches (1-4 cm) long, joined by a fringe of bristles at the stem nodes, and the stems are rough to the touch. Small funnel-shaped flowers sit singly or in pairs in the leaf axils, each about 0.2 inch (4-6 mm) wide, with four pink, lavender, or white lobes. The flowers are followed by hairy, ribbed, two-parted fruits that split into seed segments. H. teres grows in dry, sandy, and disturbed open ground, including fields, roadsides, sandy woodlands, and cultivated land across the central, southern, and eastern United States. It germinates with warm-season moisture and completes its cycle in one summer. The plant is a common weed of crops, lawns, and gardens on sandy soils, where it competes with planted species and can be difficult to control.

Native Range

Native to the central, southern, and eastern United States and parts of Mexico and the Caribbean, with naturalized populations elsewhere. It grows in dry, sandy or gravelly soils on roadsides, fields, open woodlands, pastures, and disturbed or cultivated ground.

Suggested Uses

Rarely planted by choice, it appears mainly as a volunteer in sandy fields, roadsides, and disturbed ground. Its flowers are visited by small bees and other insects, and its seeds are eaten by ground-feeding birds. In gardens and crops it is treated as a weed rather than an ornamental.

How to Identify

Recognized by its low, wiry, much-branched stems that feel rough and bear stiff, narrow, opposite leaves joined by bristly stipules at each node. The small four-lobed pink to white funnel-shaped flowers sit tucked in the leaf axils. The ribbed, hairy, two-seeded fruits set it apart within the madder family. Its rough stems and bristle-fringed nodes separate it from smoother weedy relatives.

Appearance

Size & Dimensions

Height4" - 2'

Width/Spread6" - 1'6"

Colors

Flower Colors

Foliage Colors

Bloom Information

Bloom Period

~18 weeks

Summer Fall

Flowers from summer into early fall, mainly June through October, opening in the leaf axils over a long warm-season window. Flowering continues as the plant branches and grows through the summer. Bloom slows once cooler weather arrives and the plant sets seed.

Detailed Descriptions

Flower Description

pink to white

Foliage Description

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 Range5.5 - 7.0(Neutral)

357912

Soil Types

sand loam rocky

Drainagewell drained

Water & Climate

Water Needs

Low

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Hexasepalum teres grows in full sun on dry, well-drained sandy or gravelly soils with a pH near 5.5 to 7.0 and tolerates poor, low-fertility ground. It is drought tolerant and needs no irrigation, growing through the heat of summer. The plant self-seeds heavily and reappears each year wherever soil is bare or disturbed. As a weed it is hard to remove because seedlings emerge over a long period and plants set seed quickly. It needs no fertilizer and grows readily in compacted or sandy soils. Repeated cultivation or mulching before seed set is used to limit its spread.

Pruning

No pruning is needed for this annual. Plants can be pulled or hoed before the fruits ripen to reduce seeding. Cutting or cultivating disturbed ground repeatedly through summer limits the buildup of seed.