Threadleaf Phlox (Phlox mesoleuca)

Description

Tufted, with a few slender decumbent, ascending or erect stems 15-30cm in length, sometimes more. Leaf nodes more or less widely spaced, the blades linear, somewhat grey-green, 5-8.5cm long, the mid-stem blades longest, the upper ones pubescent, glandular or not. Flowers to 3cm or more across, purple with a pale eye, pink, white or yellow with a pale eye, spring and summer. Mid northern Mexico and adjacent Texas and New Mexico at 1200-3000m, in dry open woods. Much taxonomic confusion surrounds this species and its allies mexicana, triovulata and nana. The plant usually grown as P. mesoleuca in Great Britain is P. triovulata, q.v.). Under P. mesoleuca, Dr Edward T. Wherry, monographer of the genus, placed two distinct forms of P. nana, the rich purple-pink var. purpurea and the yellow var. lutea. Professor Paul Maslin when studying some of these phloxes in the wild discovered several striking hybrids which he named (see below). He also elevated the vars. purpurea and lutea to specific rank. However, as all the above phloxes seem capable of crossing with each other, creating even more species does not seem very helpful. Chromosome studies by Dr R. Brummit of Kew suggests that both P. lutea and purpurea are no more than colour forms of P. mesoleuca. Unfortunately P. mesoleuca is not easy to grow, requiring gritty but not poor soil and warm dry summer weather to flower well; best in the alpine house. The following Maslin selections from the Sierra Madre, Mexico are in commerce in U.S.A., the British Isles and elsewhere from a few specialists. P.m. 'Paul Maslin' (P. lutea 'Paul Maslin'), canary-yellow with a purple V at the base of each petal. 'Mary Maslin' (P. lutea X purpurea) in the strict sense, is signal red and a vigorous grower. However, some nurserymen have given this name as a grex for all the lutea X purpurea hybrids, and individually to various colours, i.e. 'Tangelo', nasturtium orange; 'Denver Sunset', saturn red; 'Alborado', orange red; also to a yellow selection. 'Manzana' is soft pink; 'Vanilla' is cream and 'Arroyo' bright cerise. 'Chameleon' starts creamy yellow with deep yellow and cream Vs at the base of each petal, gradually fading to white with paler Vs.