Hylotelephium spectabile Seeds | Showy Stonecrop
LATIN NAME: Hylotelephium spectabile
COMMON NAME: Showy Stonecrop
Plant Profile
Showy stonecrop, iceplant, butterfly stonecrop: the second name is wrong, since the plant is not an iceplant, and the third is the most useful. It is native to China and Korea, from the northern provinces through Inner Mongolia and Manchuria into Primorye, and it reached European gardens in the mid-1860s, arriving in France first.
It is an herbaceous perennial to 45 cm tall and as wide, with erect unbranched succulent stems and a tuberous root rhizome. The leaves are opposite or in threes, simple, wedge-shaped at the base and frosted blue above, 2.5 to 10 cm long, with a smooth margin that turns serrated towards the tip. There are no stipules.
The flowers are star-shaped and pink, carried in flat cymes 15 cm across from summer until the first frost. Each flower is about a centimetre wide and usually five-parted, with petals 6 to 8.5 mm long and two rings of stamens longer than the petals, their anthers purple. The specific epithet simply means showy.
Science & Biotechnology
The plant has a second career in laboratories, and it is not a small one. It is a model for the synthesis of sedoheptulose, a seven-carbon sugar that sits in the Calvin cycle and accumulates in Crassulaceae as a storage product. Work on this species helped establish how the carbon skeleton is shuffled in CAM plants.
It has also been studied for phytostabilisation: the uptake and movement of heavy metals through root, stem and leaf. A plant that holds metals in its roots rather than its shoots can be used to stabilise contaminated ground without the risk that grazing animals will eat the contamination. The work is applied, not theoretical, and it is the reason the species appears in remediation trials.
The genus itself is a recent split. Hylotelephium was separated from Sedum by Hideaki Ohba in 1977, on the basis of anatomy and chromosome number rather than habit, and the old name Sedum spectabile is still in every second catalogue. The plants sold as Autumn Joy belong to neither: it is a hybrid, H. spectabile crossed with H. telephium, properly listed as H. Herbstfreude.
Uses & Benefits
The flat cyme is a landing platform, and that is why the plant is so good in autumn. Butterflies come for nectar at a height and on a surface that suits them, and a clump in September will hold commas, red admirals and small tortoiseshells at once. Bees work the same flowers, and the effect is a plant that moves.
It is also a structural plant in winter. The dried heads hold frost and stand until February, and a row of them in a gravel garden is worth more in January than the same row was in August. Cutting them down in October is the tidy choice, and it is the wrong one.
The cultivars are numerous and mostly good. Brilliant is a strong pink and holds an Award of Garden Merit, alongside the species itself. Iceberg is white and slightly later, and the purple-leaved forms have darker stems and foliage that turn almost black before the flowers open. All of them want the same thing: sun and drainage. Alongside it in Crassulaceae: Sedum selskianum, Sedum rupestre and Sedum lineare.
Growing from Seed
The seed is dust-fine and needs light. Surface sow on a firmed, moist compost, press it in without covering, and keep at 15 to 20 °C. Germination takes two to four weeks and is uneven, and the seedlings are so small for the first month that a tray can look empty when it is not.
Prick out when the rosettes are 2 cm across, handling them by the leaf rather than the stem. Grow on in individual pots through the first summer, and plant out when the rosette is 5 cm wide. Expect flowers in the second or third year; the first year goes into the tuberous root, which is the part that has to survive winter.
Division is quicker and more reliable than seed. Lift a clump in spring, and it will be hollow in the middle after four or five years; discard the woody centre and replant the outer pieces. Wet winter is the real enemy, more than cold, so plant on a slope or in gravel and keep the crown clear.
Our Take
It is overplanted, and the flat pink head has become a design cliché in the same way as the purple coneflower. That is not the plant’s fault. In a gravel garden, in a pot on a hot step, or at the front of a dry border, it is still one of the most reliable things you can put in the ground.
Cut half the stems back in late May and the clump will flower over eight weeks instead of four, at two heights, which solves the cliché problem and gives the butterflies a longer season. Let the rest stand through winter. That is the whole management plan, and it takes five minutes.
Related Reading
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