Cirsium acaulon
stemless thistle
Overview
Cirsium acaulon is a low perennial thistle in the daisy family (Asteraceae) that forms a flat rosette of spiny leaves pressed against the ground, usually with no visible stem. The deeply pinnately lobed leaves are 2–6 inches (5–15 cm) long, dark green, and edged with sharp spines. From July to September one or a few reddish-purple flower heads 1–1.5 inches (2.5–4 cm) across sit in the centre of the rosette, at or just above ground level; taller stalked forms occur occasionally on richer or ungrazed ground. The seeds carry a feathery pappus and are wind-dispersed. It grows on dry, short, grazed chalk and limestone grassland, where the ground-hugging rosette survives close grazing and trampling that remove taller plants. The species needs open, sunny, low-nutrient turf and is lost when grassland is left ungrazed and tall grasses and scrub take over. Its sharp spines deter grazing animals from the flower heads, and it spreads slowly, mostly by seed.
Native Range
Native to Europe, from Britain east to the Caucasus and south to the Mediterranean, mainly on calcareous soils. It is most frequent in warm, dry, lime-rich grassland.Suggested Uses
Cirsium acaulon is used in chalk and limestone grassland restoration, conservation meadows, and wildflower turf, where it adds late-summer nectar for pollinators. Its ground-level rosette suits short, grazed swards rather than borders or tall plantings.How to Identify
Appearance
Size & Dimensions
Height1" - 6"
Width/Spread6" - 1'
Bloom Information
Flower heads open from July to September. The reddish-purple, sweetly scented heads are rich in nectar and draw bees, butterflies, and burnet moths. Feathery wind-borne seeds ripen from late summer, though many heads are eaten by insects and birds before the seed disperses.
Detailed Descriptions
Foliage Description
dark greenGrowing Conditions
Sun Requirements
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