At one time the genus Bignonia contained many more species than it does today. In the year 1700, J. P. de Tournefort, to express his “particular esteem and veneration”, named the genus in honor of Abbe Paul Bignon, court librarian to Louis XV (Tournefort also willed his valuable botanical library to Bignon). The genus first contained about fifteen species. In 1768, when the first Index Kewensis was published, seven species named by Linnaeus were included, and were being cultivated at Kew Gardens: Bignonia catalpa, Bignonia sempervirens, Bignonia unguis cati, Bignonia crucigera, Bignonia radicans, Bignonia radiata, and Bignonia peruviana. During the next two centuries, the number increased to more than a hundred. However, botanists have reclassified these into twenty-eight new genera which make up the family Bignoniaceae. Today, not one of the original species remains in the genus, which is represented by only the single species, Bignonia capreolata L. (syn. Anisostichus capreolatus, Doxantha capreolata), a North American plant first introduced into Europe in 1710. Its native habitat is Virginia westwards to central Illinois, extending as far south as Florida and Louisiana; it is commonly known as Cross-Vine or Trumpet-Vine, and in Latin America is also known as Bejucos de la cruz (Cross-vine). This common name associating the plant with the Cross is due to an unusual characteristic of the stem; when a transverse cut is made, four centrally converging wedges forming a cross may be seen. This was sufficient to endow the plant with an aura of sanctity.
Cross-vine is a glabrous evergreen climber with stiff leaves; the leaf stalks terminate in branching tendrils enabling the plant to attach itself to any object over which it climbs. The foliage is opposite, divided into two sections, oblong-lanceolate, dark greenling, heart-shaped at the base, and pointed. The flowers stalked and abundantly produced in axillary racemes, are orange-red externally, yellowish internally. The corolla is funnel-shaped, up to long, and wide at the mouth where it spreads into five rounded lobes. In a warm climate, seeds are freely produced in 6-in.-long, narrow flat pods which offer an easy method of propagation.
Cultivation. Bignonia capreolata is one of those plants whose hardiness is difficult to define. In areas where summers are long, hot, and dry so that the wood becomes thoroughly mature and ripe, old specimens can certainly tolerate severe cold `if established in a sheltered position. But young specimens growing in shaded positions and subject to dull, wet summers will develop soft, sappy growths and can be killed by much less intense cold. As the experienced gardener well knows, hardiness is closely related to the position where a plant is grown, and in the United States and Europe—where there is a wide diversity of climate—the only definite solution to the question of hardiness is the system of trial and error.
I have noted that even in the same garden, plants such as Bignonia capreolata are hardy in one position and not hardy in another possibly only a few yards distant. In colder countries, this attractive climber may be cultivated as a cool-greenhouse subject, although, because of its size and rampant habit, and because it does not bloom until the plant has reached maturity, it is suitable only for very large structures. It requires a heavy, fibrous, and fertile soil; plenty of light, and a well-aerated position. Abundant watering is beneficial in summer, but in winter the plant is more or less dormant. In the case of greenhouse specimens, some authorities advise planting in boxes. deep so as to restrict the development of its vigorous root system; a procedure that limits the plant’s exuberant growth and increases its flowering capacity. A winter temperature of about 45°F. is sufficient for greenhouse-grown plants; gradually raise this temperature and increase ventilation as the days lengthen. Spray the foliage with water daily when the plant is not in bloom. Bignonias are particularly susceptible to infestations of mealy bugs, and the plants tend to harbor other insect pests. Occasional spraying with kerosene and water or with one of the excellent commercially available insecticides should keep the plants pest-free.