The genus Sedum, commonly known as Stonecrop, encompasses a vast and popular group of succulent plants celebrated for their hardiness and diverse visual appeal. With hundreds of species, the term “Sedum” describes a wide array of plants, from low-growing mats to upright clumps, all unified by a specific, water-retaining structure. These perennials are favored by gardeners for their ability to thrive in poor, dry conditions, often providing color and structure when many other plants fade. To visually identify a Stonecrop, one must focus on the unique physical characteristics that define its leaves, stems, and overall growth habit.
The Defining Feature: Succulent Leaves and Stems
The most immediate visual cue for identifying a Sedum is its succulence, which allows the plant to store water in its thick, fleshy tissues. The leaves are the primary water reservoirs, appearing plump, dense, and turgid, which is an adaptation for surviving dry environments. This water-storing capacity gives the foliage a rubbery or waxy texture. The shape of these leaves is highly variable, ranging from small, rounded, or oval forms to pointed, lance-like, or even cylindrical, needle-like structures, such as those found on Sedum rupestre ‘Angelina’.
The color palette is diverse, with foliage appearing in shades of bright green, blue-gray, smoky purple, yellow, or even variegated patterns. Some varieties exhibit a bluish-green hue due to a waxy coating known as a glaucous bloom. The stems of most Sedums are also slightly fleshy and robust, contributing to the plant’s structural integrity. In some cultivars, like Sedum ‘Matrona,’ the stems themselves can be a deep maroon or purple, providing a contrasting visual element to the leaves.
Distinguishing Between Upright and Creeping Varieties
For identification purposes, Sedums are broadly categorized into two distinct growth habits: upright and creeping. Upright varieties form dense, vertical clumps. These plants are substantial, typically growing between one and two feet in height, making them excellent choices for borders and mixed perennial beds.
A classic example, like Sedum ‘Autumn Joy,’ features thick, sturdy stems that hold the foliage and late-season flowers. The base of these upright plants often becomes slightly woody with age. Conversely, creeping or mat-forming Sedums are low-growing, ground-hugging plants that rarely exceed a few inches in height. These varieties, such as Sedum spurium or Sedum album, have a spreading habit, creating a dense, often evergreen mat of foliage that works well as groundcover or in rock gardens.
The low-growing types spread by rooting along their stems as they creep across the soil surface, forming a durable carpet. While the upright forms provide vertical interest, the creeping varieties are characterized by their horizontal spread and shorter stature. The structural difference between the tall, robust clumps and the short, sprawling mats is the clearest way to determine the type of Stonecrop being observed.
Seasonal Appearance and Identifying the Blooms
Sedum blooms are highly recognizable, typically appearing as small, star-shaped flowers with five petals. These tiny blossoms are not solitary but are clustered tightly together in dense, flat-topped or dome-shaped inflorescences called cymes. The common flower colors include white, various shades of yellow, pink, and vibrant red, depending on the specific species or cultivar.
The timing of the blooms also aids in identification, as the low-growing, creeping varieties often flower earlier, typically in late spring or early summer. In contrast, the tall, upright Sedums are prized for their late-season color, blooming from late summer through the fall. A notable feature is the color transformation of the flower heads on upright types, which often start out green or light pink and gradually deepen to shades of rosy-pink, russet, or coppery-red. Many Sedum varieties maintain their dried flower heads and colorful foliage through the winter months, offering a persistent architectural presence in the landscape.