Leptinella, commonly known as Brass Buttons or Cotula (although the latter is a broader genus). These low-growing plants offer a unique texture and are excellent for specific garden situations.

What Makes Leptinella So Special

• Tiny, Fern-Like Foliage: Leptinella species are characterized by their very small, finely divided, fern-like leaves. This creates a dense, carpet-like effect that is quite distinctive.
• Low-Growing, Spreading Habit: They are excellent ground covers, forming a tight mat that hugs the ground.
• Button-Like Flowers (Sometimes): Some species produce small, button-like flower heads (hence the common name "Brass Buttons"), which are often yellow or greenish-yellow. However, the flowers are not always the main attraction; the foliage is often the primary reason for growing these plants.
• Traffic Tolerant (Some Species): Some Leptinella species, particularly Leptinella squalida 'Platt's Black', are surprisingly tolerant of light foot traffic.
• Unusual Texture: The fine, fern-like foliage provides a unique texture that contrasts well with other plants.

Description and Details

• Growth Habit: Low-growing, creeping, mat-forming perennials (some can be grown as annuals in colder climates).
• Stems: Slender, creeping stems that root at the nodes, allowing the plant to spread.
• Leaves: Very small (often less than 1 cm long), alternate, pinnately compound (divided into leaflets), and fern-like. The foliage color varies depending on the species and cultivar, ranging from green to bronze, purple, or nearly black.
• Flowers: Small, button-like flower heads (capitula), often yellow or greenish-yellow. They are not always showy and are sometimes absent.
• Fruit: Small, dry achenes (single-seeded fruits).
• Size: Typically grows to only 2.5-5 cm (1-2 inches) tall but can spread indefinitely.

Commonly Cultivated Species and Cultivars

• Leptinella squalida (New Zealand Brass Buttons): A popular species with green, fern-like foliage. 'Platt's Black' is a very popular cultivar with dark purplish-black foliage.
• Leptinella potentillina (also known as Cotula potentillina): Has larger, more coarsely divided leaves than L. squalida.
• Leptinella dioica: Another New Zealand native with green foliage.
• Leptinella minor: Smaller leaves.

Native Habitat

• Origin: Most Leptinella species are native to New Zealand, Australia, and South America.
• Typical Habitats: Found in a variety of habitats, including coastal areas, grasslands, alpine regions, and damp places.

Landscaping Design Tips

• Ground Cover: Their primary use is as a ground cover, particularly in small areas or where a very low-growing plant is needed.
• Between Paving Stones: Excellent for filling in gaps between stepping stones or pavers, creating a soft, textured "mortar."
• Rock Gardens: Well-suited for rock gardens, where their low growth habit and interesting foliage can be appreciated.
• Fairy Gardens: Their miniature scale makes them perfect for fairy gardens and miniature landscapes.
• Lawn Alternative (in small areas, with light traffic): Some species, like 'Platt's Black', can be used as a lawn substitute in small areas where foot traffic is light.
• Container Planting: Can be used in containers, spilling over the edges.
• Underplanting: Plant under taller specimens in containers.

Planting and Care

• Planting:
• Timing: Plant in spring or early fall.
• Spacing: Space plants 15-30 cm (6-12 inches) apart.
• Soil: Prefers well-drained soil that is moderately fertile. It tolerates a range of soil types, including sandy, loamy, and even somewhat poor soils. Avoid heavy, wet soils, which can lead to root rot.
• Light: Varies depending on the species. Some prefer full sun, while others tolerate partial shade. Leptinella squalida 'Platt's Black' generally does best in partial shade, as full sun can scorch the foliage in hot climates.
• Care:
• Watering: Water regularly during the first growing season to establish a deep root system. Once established, most species are relatively drought-tolerant, but they will perform best with consistent moisture, especially during dry periods.
• Fertilizing: Generally, they do not require fertilization. In very poor soils, a light application of a balanced fertilizer in spring can be beneficial.
• Pruning: Pruning is usually not necessary, but you can trim back any straggly growth to maintain a neat appearance.
• Weeding: Remove any weeds that appear, especially when the plants are young. Once established, the dense mat of foliage will help suppress weeds.
• Pest and Diseases: Generally, pest and disease resistant. Root rot can be a problem in poorly drained soils. Slugs and snails may occasionally feed on the foliage.
• Propagation: Easily propagated by division. Simply dig up a clump and separate it into smaller pieces, each with roots.

Taxonomy

• Kingdom: Plantae
• Phylum: Tracheophyta
• Class: Magnoliopsida
• Order: Asterales
• Family: Asteraceae (Sunflower family)
• Genus: Leptinella
• Synonyms: Cotula (some species previously classified in this genus)

Morphology

• Root System: Fibrous root system with creeping rhizomes.
• Stems: Slender, prostrate (growing along the ground), and rooting at the nodes.
• Leaves: Small, alternate, pinnately compound (divided into leaflets), and fern-like.
• Flowers: Small, button-like flower heads (capitula), often lacking ray florets (the "petals" of a typical daisy). The disk florets are usually yellow or greenish-yellow.
• Fruit: Small, dry achenes (single-seeded fruits).

Other Insights for Gardeners

• 'Platt's Black' Color: The dark purplish-black foliage of Leptinella squalida 'Platt's Black' is its most distinctive feature. The color is most intense in cooler weather and with some shade.
• Traffic Tolerance: While some Leptinella species are tolerant of light foot traffic, they are not as durable as turfgrass. Avoid heavy or concentrated traffic.
• Invasive Potential: Generally not considered invasive, although they can spread readily in favorable conditions.
• Cold Hardiness: Hardiness varies among the species.
• Availability: Leptinella squalida 'Platt's Black' is widely available at nurseries and garden centers. Other species may be harder to find.

In conclusion, Leptinella offers gardeners a unique and charming ground cover option. Their tiny, fern-like foliage creates a beautiful texture, and their low-growing habit makes them perfect for filling in gaps, softening edges, and adding a touch of whimsy to the garden. While they may not be the showiest plants in terms of flowers, their foliage and versatility make them a valuable addition to a variety of garden settings, especially rock gardens, fairy gardens, and between paving stones.