PHLOX: AN EXPLORATION

PHLOX IN HORTICULTURE

Primrose Path Home

Introduction

What is a Phlox?

Basis of Breeding

Accounts of Species and Cultivars

References

Phlox paniculata

The earliest phlox to be cultivated was P. paniculata, which was sent to Europe from Virginia in the early 18th century. Selected forms were on the market by the early 1800s in England and by the mid 1800s in France. The earlier modern selections of P. paniculata were made during the mid 1900s in England by Symons-Jeune (reviewed by Symons-Jeune 1953) and Alan Bloom (reviewed by Bloom 1991) and in Germany by Georg Arends. Present day P. paniculata breeding takes place for the most part in The Netherlands and the United States

Symons-Jeune and Bloom selected mostly for flower size and color and for vigor. Although Symons-Jeune seems to have had little understanding of the basis of inheritance (cf. Symons-Jeune 1953, p. 81) he was a skilled breeder, and many of his selections are still in the trade. Many of Bloom’s selections, too, have become standard varieties. Arends was basically a hybridizer and experimented with crossing P. paniculata with other species. Some of his P. paniculata P. divaricata hybrids are still available.

These breeders explored the range of flower colors pretty thoroughly, and present day breeding focuses on other traits. The Dutch have been concerned for the most part with growth habit, although there has been interest also in novelty floral mutations. Breeding has involved reduction in height to 50-60cm combined with sturdy stems and large flower heads. This trend is similar to that for many other perennials in The Netherlands, where there is an emphasis on pot presentation and shipping efficiency. There have been some very handsome new plants of traditional height, though, most notably selections like ‘Valentina.’ In the United States selection has emphasized resistance to powdery mildew. Some apparently resistant varieties are much closer to wild types in flower color and growth habit than are those bred in Europe.

Other tall and mid size species

P. divaricata also reached England from Virginia by the first half of the 18th century. Symons-Jeune (1953) lists 10 named selections of P. divaricata available, but in the 2008 RHS plantfinder these have been replaced by new forms, almost all of which are US selections from wild populations. Hybrids of P. divaricata P. paniculata (P. arendsii) were offered for sale by Arends nursery by 1912. New cultivars of P. arendsii continue to come onto the market. It is not clear if these are F1 hybrids or derived from seed made by P. arendsii parents.

Other members of the P. divaricata group have been grown in gardens since the 1800s, but named cultivars seem to be all selections from the wild. A few hybrids, such as P. pilosa P. divaricata and P. amoena P. divaricata are grown. These are selections from the wild or garden hybrids, and breeding does not seem to have been done past the F1 generation.

The P. glaberrima group made its way to Europe by the mid 1700s, too. P. maculata was used by Arends as a hybridization parent with other phlox, although the results of his crosses do not seem to have survived. Selections have been made of P. maculata, most notably by Alan Bloom, and at the present time about a half-dozen cultivars of this species are available. P. carolina and P. ovata reached England by the 1700s and P. pulchra by the 1950s. They have been grown as garden plants, but nothing seems to have been done to develop new cultivars of these in Europe. In North America this group has been almost ignored by mainstream gardeners except for a few cultivars of P. maculata. The species are grown mostly by native plant enthusiasts, although a couple of recent cultivars, P. glaberrima ssp. triflora ‘Morris Berd’ and P. carolina ‘Minnie Pearl’ are increasingly popular. True P. glaberrima and P. amplifolia do not seem to be in garden use. This group has had a checkered taxonomic past, and the names of the species and cultivars offered by nurseries are very confused. The British have tended to continue to use obsolete species names, and the errors and inconsistencies of authors like Symons-Jeune (1953) have not helped.

Named selections, mostly of wild finds, have been introduced of P. stolonifera and P. adsurgens. A few hybrids of P. stolonifera P. subulata and P. adsurgens P. nivalis have been made and introduced but are not mainstream garden plants.

Moss Phlox

Phlox subulata reached Europe almost as early as P. paniculata. Many cultivars have been selected there and in North America. P. bifida and P. nivalis came into cultivation by the early 1800s, and a significant proportion of moss phlox available are hybrids of these species with P. subulata. Some of the western moss phlox are growable by alpine gardeners in Europe. Hybrids have been made by British, German, and Czech growers of western species with (apparently) P. subulata. These small and very choice cultivars often do well in the eastern US, but are too small to be grown by other than rock gardeners.

 

 

[Introduction] [What is a Phlox?] [Basis of Breeding] [Accounts of Species and Cultivars] [References