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Senecio viscosus

sticky groundsel

Attracts Pollinators Deer Resistant Drought Tolerant

Overview

Senecio viscosus is an annual herb in the daisy family (Asteraceae), growing 4–24 inches (10–60 cm) tall and covered throughout in sticky glandular hairs that give it a clammy feel and a strong, unpleasant smell. The greyish-green leaves are deeply pinnately lobed, 1–4 inches (2.5–10 cm) long, and stalked. The flower heads are 0.4–0.6 inch (10–15 mm) across with yellow disc florets and short outer ray florets that curl back and outward; they are held in a loose, branched cluster from July to September. Below each head the bracts are tipped black and backed by short spreading scales. The seed is a ribbed achene with a white pappus that carries it on the wind. It grows on dry, open, disturbed ground such as railway ballast, shingle, walls, waste places, and gravelly roadsides, on sharply drained, often stony soils. As an annual it sets abundant seed and needs bare ground, and it disappears once the surface closes over with grass or perennial cover.

Native Range

Native to Europe and western Asia. It has spread widely as an introduced weed of bare and disturbed ground, including parts of North America, often along railways and ports.

Suggested Uses

Senecio viscosus is not grown ornamentally or as a crop and is regarded as a weed of railways, waste ground, and gravel. It has minor value as a late-season nectar source for small pollinators on otherwise bare sites.

How to Identify

Recognized by the sticky, glandular hairs that coat the whole plant and the strong foetid smell when touched. The greyish, deeply lobed leaves and the yellow flower heads 0.4–0.6 inch (10–15 mm) wide with short, backward-curling ray florets separate it from common groundsel (Senecio vulgaris), which is nearly hairless and usually lacks ray florets. Black-tipped bracts and a basal ruff of short scales sit beneath each head.

Appearance

Size & Dimensions

Height4" - 2'

Width/Spread6" - 1'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~12 weeks

Summer Fall

Flower heads open from July to September, sometimes into October. Pollination is mainly by small flies and bees, though the flowers also self-pollinate. Wind-borne seed with white pappus is shed from late summer onward, allowing several overlapping generations in a warm season.

Detailed Descriptions

Foliage Description

greyish-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 - 7.5(Neutral)

357912

Soil Types

sand rocky loam

Drainagewell drained

Water & Climate

Water Needs

Low

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Senecio viscosus grows in full sun on dry, sharply drained, stony or sandy ground and needs no cultivation, feeding, or watering. It germinates on bare gravel and waste ground from spring to autumn and completes its cycle in a single season. The sticky foliage tends to trap dust and small insects. In gardens it appears as a self-sown weed on paths, gravel, and disturbed soil, where hoeing or pulling before the pappus forms reduces seeding. Plants contain pyrrolizidine alkaloids and are poisonous to grazing animals if eaten in quantity.

Pruning

No pruning is required for this annual. Removing the flowering stems before the seed heads open limits self-sowing the following year.

⚠️ Toxicity Warning

Toxic to pets and humans