Of Twists & Turns: What are crested plants?

Why do plants crest?

The exact cause of cresting, also known as fasciation, can vary, and may include genetic mutations, viruses, or physical damage to the growth point. To understand cresting and crested plants, one must first understand the basics of how a plant grows.

Plants consist of a variety of different tissues, and these perform several different functions. Meristematic tissue is what causes active growth in plants. This tissue contains cells that are able to divide, and form new tissues, much like stem cells in humans. Meristems are present at the tips of roots, stems and branches of plants, and are what allows the plant to grow these organs. The apical meristem, or main growing point in the stem of the plant, is responsible for the normal, vertical growth of most plants. It is focused on a single point and forces the plant to grow upwards, or the roots to grow downwards.

However, with any cell that can divide, there is always the chance that something can go wrong. In a crested plant, the apical meristem, which is normally a single growing point, divides into multiple smaller points. The apical meristem then grows in a horizontal instead of a vertical point, which leads to the development of a contorted appearance. Each crested plant has its own unique form, which makes them highly sought-after by rare plant collectors.

Crested succulents

Euphorbia is one of the succulent genera that tends to have the most intriguing crested forms. Euphorbia pugniformis forms thin, green, wave-like stems with tiny leaves on its edges. The clusters can become exceptionally large, if given enough growing space, and will do so quickly. In contrast, Euphorbia obesa retains its usual robust stem, and then elongates, but grows exceptionally slowly. Many other species including Euphorbia lactea, Euphorbia triangularis and Euphorbia alluaudii also have beautiful crested forms.

Aeonium of all species and cultivars are likely to crest, due to their fast growth rate. In fact, Harry’s first ever crested plant was an Aeonium ‘Schwarzkopf’ from a retail nursery. Aeonium ‘Sunburst’ crests are relatively common in collections these days. Crested specimens of Aeonium tabuliforme, Aeonium ‘Fiesta’, Aeonium ‘Velour’ and Aeonium ‘Halloween’ are also available in the horticultural market.

Echeveria also have a tendency to become crested, for similar reasons to Aeonium. Each species tends to produce different shapes, depending on the stem and leaf structure.

Other succulents, such as Sempervivum, Crassula, Stapelia and Pachyphytum may also form crests. On extremely rare occasions, plants with very minimal stems like Haworthia, Gasteria and Agave can also form crests, but this almost never happens, and is generally only seen in tissue cultured specimens.

Crested cacti

Cacti have even more variable crested forms than succulents, with each species having its own unique form. In many cases, there are even multiple different crested forms in one species.

In tall, column forming plants like the San Pedro (Trichocereus pachanoi) and Trichocereus bridgesii, cresting usually manifests itself as a flattened expansion of the original plant stem. This mutation causes an almost flag-like, horizontal growing structure to replace normal, vertical growth at a certain point on the stem. The Giant Saguaro cactus (Carnegiea gigantea) is also quite famous for forming crested stems in its natural habitat.

Cresting is different in smaller plants that grow closer to the ground like Mammillaria. Specifically, the famous Mammilaria elongata (‘Brains Cactus’) in its crested form makes the plant fold in on itself. This gives it the appearance of having an unending number of twists and turns.

Gymnocalcyium also takes on a variety of different crested forms, and can form secondary crested stems. This habit gives the plants quite an artistic and sculptural appearance.

Other crested plants

Plants that have more prominent stem structures are more likely to become crested than those that do not. The more stem there is, the more chance there is for a mutation to occur. However, it is not just the stem of a plant that can crest. The aforementioned Agave and Haworthia can produce crested flowers, even if their stems almost never crest. Some flowers like Celosia have been cultivated specifically as crested forms for the ornamental and cut flower trades. Lastly, while our focus is on cacti and succulents, everything from trees, shrubs and even common garden weeds can become crested.

Written by Harry Lewis, succulent specialist & conservationist