Many plants of the genus Bignonia have been, in recent decades, gathered in another genus, the genus Campsis; in particular, nowadays all the bignonie that are commonly cultivated in Italy belong to this genus. The most widespread species, also present in the gardens of our grandmothers, is campsis radicans, a species of American origin, with large orange flowers, and particular aerial roots, which allow the plant to attach itself to any surface; in addition to campsis radicans, we find in Italian nurseries and gardens, also Campsis grandiflora, native to Japan and Asia, which instead, to be cultivated as a climber, needs to be fixed to the guardians, and therefore is often cultivated in pot or as shrub; also widespread Campsis radicans var. flava, with yellow flowers, and Campsis x tagliabuana, a variety with very large flowers, almost red in color.
In general they are vigorous and thriving climbing plants, resistant to cold, with pinnate leaves, consisting of lanceolate leaflets, with a serrated margin, light green, deciduous. From the beginning of summer until autumn, the campsis produce large trumpet flowers, in shades of orange, gathered in large bunches, which contain from six to ten or twelve large flowers. It is a plant of easy cultivation, which has received and is very successful; in the last decades some varieties have been selected, with very large flowers, or even with flowers of a decidedly very bright color, almost flaming red.
This climber is grown outdoors, in pots or in the open ground; during the winter it is in complete vegetative rest, and loses its foliage, which is why it tolerates cold and frost very well, and does not need protection; some varieties or species, such as Campsis grandiflora, may fear very intense frost, and must therefore be planted in areas sheltered from the wind, if we live in a place where winter temperatures are often below -10 ° C. They are vigorous plants, which tend to produce many basal shoots, and an annual growth that reaches even a few meters in length, so they are positioned in an area where it is possible to let them develop freely, such as near a pergola or a gazebo. They are cultivated in full ground, or in large pots, in a good porous soil and very well drained, light, even if they bear to live in any substratum, even in the common garden soil; at the time of implantation, the soil is enriched with a little manure, or with a slow release fertilizer; during the following years, the fertilizer of potted plants is generally fertilized, while in general it is not necessary to practice this operation for plants cultivated in the open ground, unless they are in a decidedly very poor nutrient or stony soil.
Watering is provided at the time of implantation; later, the adult specimens can be satisfied with the water supplied by the rains, but the plants that have recently settled down may need watering in the summer period, especially during flowering or in particularly dry and rain-free periods. They do not like water stagnation, and excess water in the soil, so they are watered only in summer, and only when strictly necessary. Clearly, the specimens grown in pots will have to be watered regularly, whenever the soil is decidedly dry, avoiding excesses, and avoiding leaving stagnant water in the saucer.
Pruning is practiced at the end of winter, removing all the damaged or particularly thin branches; in general, strong pruning tends to decrease the number of flowers produced, therefore they are practiced only when the plant is very large, or particularly damaged by the winter climate. At the end of summer, when the plant no longer produces any flowers, it is useful to shorten all the branches at the apex, to give the plant a more compact and contained posture.
Multiply the Bignonia
These plants root with great ease by cutting, taking the semi-woody tips of the branches that do not carry flowers, in summer or at the end of spring; the twigs should be divided into portions of about 10 c in length; the leaves in the lower part are detached and the lower part of the branch is cut in oblique motion, so that the cutting surface is as wide as possible. Then the lower part of the cutting is immersed in the rooting hormone, and then it is buried in a compound consisting of peat and sand in equal parts, which must be kept moist until the cuttings give no sign of having rooted, producing shoots. The young plants thus obtained will have a flowering identical to that of the mother plant; they should be stored in a sheltered place, with temperatures no lower than 5 ° C, until they are large enough to be planted in the garden.
The flowers are followed by small fruit trees, which bear some seeds, usually fertile; the plants obtained from seed, however, will certainly not be identical to the mother plant, if it is a hybrid; so if we see one bignonia with very particular flowers, it is convenient to ask to be able to take some cuttings, rather than collect the seeds. They are sown in autumn, in jars that are then left outdoors, but in a place fairly sheltered from the cold; they will germinate in the spring.
The corolla of the bignonia it has a particular form, much appreciated; the five petals are welded to the base, to form a sort of thin cone; at the apex, on the other hand, the petals widen to form a sort of wide labellum, these lobes give rise to what we might call a kind of trumpet. In nature there are many flowers with this shape, or a similar shape. The size and color of this type of holes make them very much appreciated. The most common trumpet flowers are surfinie and petunias, with their flowers of the most varied colors, from white to yellow, from pink to intense blue, which sometimes appear to be made of velvet.
The larger trumpets are instead perhaps those of brugmansia and datura, which attract us for their decidedly large dimensions. Also the convolvulaceae often produce trumpet-shaped flowers, with the tip of the petals still welded together, without lobes; the convolvolus cneorum has white flowers, but the thousand varieties of morning glory cheer us with flowers of all colors, and of large dimensions. Also the oleander flowers have this hole, but the tubular base is definitely much shorter than that of the bignonie; the glossinias (sinningia speciosa) with a broad and broad "tube" and frayed lobes are also of particular shape, the color is always decidedly very bright, for a very pleasant effect.
And the list goes on and on: catalpa, paulonia, weigelia, kolkwitzia, Jacaranda, Bouvardia, Pentas, Jasmine.
Few people know that even the asteraceae have tubular flowers, that is, they consist of a thin and small tube; the flowers of asters, daisies, sunflowers, are gathered in inflorescences called flower heads, which can count up to thousands of flowers; the real flowers are those that we can observe in the central disk of the inflorescence, and they are arranged next to each other, tightly attached; the flowers placed in the external area of the inflorescence have one or some petals, to form what we often think is the corolla of the flower, these particular petals, very large compared to the flower, are called ligules, and are characteristic of asteraceae.