From dry to wet: Buttercups occur everywhere in nature and in the garden, sometimes bred differently with attractive flowers. We present a closer look at the genus.
The buttercup (Ranunculus) is a genus from the Ranunculaceae family. This includes around 600 species including annuals and many deciduous, sometimes also evergreen shrubs. Some of these can be found bred as attractive shrubs along pathways and around ponds in our gardens. Ranunculus grows from the tropics to the far north, the most widespread region for buttercups is in temperate climates: There are around 60 species in central Europe, and even more in North America. They are at home in a wide variety of living areas: They can be found in damp forests and meadows, on landfill sites in the mountains up into the high Alpine steps, on dry, sparse grasslands, and in swamps or flat water zones with standing or flowing waterways.
Almost all Ranunculus species are poisonous, whereby after flowering, the poisonous content of protoanemonine in the leaves is particularly high. Cattle and horses avoid the plants when they are green due to the bitter taste. It is common to see veritable islands of buttercups in meadows as they are left standing by grazing animals. The poison becomes harmless in dry hay.
Buttercups have varied appearances and are available in a wide range of variants, from huge to tiny: they come in all shapes and sizes. The foliage generally forms a basal rosette, often encircling the stalk. The leaves on the stem are alternating and very occasionally opposite. There are no stipules. The genus which gave rise to the German name, such as the meadow buttercup with pinnatifid foliage that is omnipresent in meadows, is reminiscent of crow’s feet (with a little imagination). The genus Ranunculus is also a diminutive form of the word “rana”, the Latin term for frog. This is an indication that many species of buttercup appear together with frogs near waterways. The leaves can be simple, for example orbiculate or cordate; the margin serrated or entire. Species of buttercup that are native in or near water, such as the water crowfoot, form special floating leaves. If they flood into water, they are divided into filamentous segments.
Some buttercup plants are cultivated in the garden for their flowers. The flowers are bowl, cup, or shell shaped. They are usually five, and occasionally three-petaled and are radiant in yellow or more rarely white, pink, orange, or red. The stamens are numerous and located in the center of the flower. Depending on the species, the flowers appear between spring and fall and are individual or in panicles.
Members of the buttercup genus have rhizomes, bulbs or also roots or off-shoots. The classic example of the latter is the creeping buttercup (Ranunculus repens) that can develop entire plant stocks with its overground roots and become a great nuisance as a garden weed. Small nutlets are typical buttercup fruit formations; here, the pericarp and seed shell are stuck together or even fused into one another. Sometimes they have a short nib.
The different root systems make one thing clear: The amplitude of growth for the buttercup genus is wide, and they can be used with according versatility in the garden. Each species also has its own soil preferences. All members are frost-hardy, with the exception of the Ranunculus that originate from the Near East (Ranunculus asiaticus) and are not used to frosts in their native home. They are primarily available as potted and cut flowers in trade shops in the spring.
Buttercups that flower in the spring should be planted in the fall, depending on the species, to ensure that they have time to take root before the winter, whereas summer bloomers can be planted in the spring. The buttercup needs special treatment.
As a precaution, gloves and long-sleeved clothing should be worn for all maintenance work: Contact with buttercup sap can lead to skin irritation. Picking buttercups and lying on the plants can cause phytophotodermatitis, resulting in redness and blisters. Consuming the plant leads to a burning sensation in the mouth, oral mucous irritation, cramps and diarrhea. Kidney damage can occur in extreme cases.
Types of wild species work well in shrub beds supplied with plenty of water, species that originate from high Alpine areas are suited to rock gardens. There are also numerous buttercup family members for water edges; these can grow in various water depths. The early flowering lesser celadine is despised by some gardeners due to its ground-covering growth on damp beds. However, it does recede again by May. However, Ranunculus ficaria also definitely has its benefits as an important provider of vitamin C in the spring. The lesser celadine should help to combat spring fever; it was previously used to treat scurvy. The root ball sap is used to treat warts - hence the name pilewort, as the bulbs look similar to condylomata. Members of the buttercup family are predominantly used to treat skin diseases in medicine.
Buttercups can be sub-divided into various groups according to their requirements:
• Species that were originally at home in forests prefer to grow in shade or semi-shade. The soil here is damp and humus-rich. A typical example is the aconite-leaf buttercup (Ranunculus aconitifolius). The plant grows up to 23.62 inches tall and forms real tall forb communities at heights of up to 8202.1 feet.
• Many undemanding Ranunculus members that grow in shrub beds or rock gardens prefer a damp soil with a good supply of nutrients; the soil should certainly be permeable. The bobble-like double-flowered variety ‘Multiplex’ is a particularly beautiful buttercup that has a nostalgic effect. The wild form is the common buttercup or meadow buttercup (Ranunculus acris) that often flowers in meadows and is probably recognized by all.
• High mountain members such as the Alpine buttercup (Ranunculus alpestris) prefer to grow in sunny locations on gritty, well drained soil. A mixture of coarse sand or grit, loam and leaf compost is a suitable substrate for the plants.
• Species that originate from water edges or swamps also like a substrate with a good water supply in the garden. Some members such as the white water-crowfoot (Ranunculus aquatilis) or tongue-leaved crowfoot (Ranunculus lingua) can even be planted in standing or flowing water. They naturally clean the water garden ponds by removing nutrients and reducing sun rays. In this way they reduce algae growth.
• Bulb forming buttercups thrive under very different conditions: They prefer it dry in the summer and really sunny during their spring flowering period. The lesser celandine (Ranunculus ficaria) is one of the “little wild ones” and is one of the first to flower, often as early as February, thanks to its bulb. It spreads its flower carpet under deciduous trees and bushes on soil with a good water supply in the early spring. There are now lots of interesting varieties in every color, including double-flowered varieties. ‘Alba plena’ has delicate yellow, double-flowers. ‘Coppernob’ has an egg-yolk yellow flower color. Orange flowers are typical for the varieties ‘Aurantiacus’ and ‘Nariane’. A further member is the bulb butter cup (Ranunculus bulbosus), that can always be seen on meadows with poor soil.
• The Ranunculus known as Asian buttercups, are becoming more and more important in garden centers in particular. There are now members with imposing flowers with a diameter of almost 1.97 inches in the most splendid, generally intense colors, often with a contrasting margin. The varieties here are not yet defined, they are simply sold according to colors.
Most Ranunculus species can be sown in potting soil, some need a cool phase to germinate. Bulb-forming species should be planted in spring or fall, depending on the flowering period, established horsts can also be divided in the spring or fall.
Snails love to go for buttercups. Aphids will usually appear if the location conditions are not appropriate. Downy mildew is particularly common on buttercup members that grow in or near water.