February 2019

The Calyx

Buds carry the promise of spring, of brilliant colour, of delicate green, fleeting messengers of warmer weather, transformative structures. They are the underdeveloped shoots from which embryonic leaves or flowers arise. Before these structures emerge, the buds are held in a protective casing, the calyx. A calyx is rarely colourful, often unremarkable and varies from species to species with a range of measures to aid protection and a diversity of other functions to support the plant’s survival and reproduction.

The calyx holds the whorls of a flower; it can be fused into a single protective layer or made from overlapping sepals. A calyx has thick cellular walls, sometimes rich in chemical compounds that discourage insect predation or secreting a moist and sticky protective liquid or containing sepal nectaries, attracting ants to guard the embryonic plant parts. Inside the calyx of a flowering bud is the corolla, the vivid petals, themselves protecting the reproductive parts of the flower, the stamens and carpels.

During winter the calyx holds the bud tightly furled, while it is at risk of desiccation, frost, rain, snow and the feeding of destructive predators. The protection is transitory, as the bud swells taking in moisture, encouraged by warmth, the calyx ruffles and opens. In some cases the sepals fall as the bud opens, in others the calyx remains, providing a ridged support to the unfurling petals. In some species the calyx is green and leaf like, in a few it is extravagantly coloured, an attractive additional whorl to the flower or a substitute where petals are absent. The calyx can persist to the fruiting stage of the plant’s development, enlarging to carry the fruit on the wind, dispersing it to find fertile ground.


Magnolia’s flower early, their petals emerging from large downy calyces. On the shrub they resemble small, soft furred, creatures. Long, silvery, silken hairs catching the watery late winter light. The furry outer coatings help protect the buds, dropping when they open, to reveal the blousey flowers. 

Narcissi flower early too, at risk from early spring squalls. The buds are folded in a buff, wrinkled, papery sheath. The single, delicate wrapping may contain one or many flowering buds.  The outer petals of the flower are in fact segments of the calyx, corolla complex, tepals, visually indistinguishable from petals.


The familiar spreading chestnut tree was introduced in the 16C from the Balkans, known for their stout, shiny, reddy brown, ‘sticky buds’. The horse chestnut calyces have a scaly, leaf like form with a resinous protective coating to prevent any penetration of damp or frost. The buds rapidly develop as the air warms towards spring, the thick, gummy coating melts and the large flowers and leaves rise up and open out.


Abutilon Kentish Belle has an arching habit, dark green pointed leaves and pendant, belle shaped flowers growing along purple brown shoots. The flower’s closed yellow petals are enfolded in a fused, deep red calyx, the strong contrast bringing dramatic charm and encouraging pollinators.

The Oriental poppy is encased in a rounded, green calyx covered in rough, bristly hairs. The stems and leaves have a similar colour and surface. As the calyx cracks open the vibrant crushed petals emerge and unfurl. As the bud opens the sepals fall off leaving the delicate, flopping petals to support themselves. 

Phasylis, Cape gooseberry, have a persistent calyx. Yellow flowers emerge from the bulbous, green bladder. After the petals have fallen the fruit develops and the calyx continues to grow forming a decorative, papery shield around the berry.

The calyx is an important structural plant part, its function is vital, defensive, but its features are rarely noticed. It is not the most striking element of a plant, its existence may be fleeting, disguised by winter’s grey, outshone later by showy petals and extravagant leaf forms. But calyces are wonderfully varied; the structure and texture of a calyx are intrinsic to individual species, a recognisable characteristic form with a quiet, distinct beauty.