This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Tall perennials with rather showy flowers remarkable for the inflated calyx and inflated bilabiate corolla enclosing four stamens. The species are natives of North America and Asia. The name is from a bladder, and to cover, in allusion to the inflated flowers.
1. Ph. imbricata. - A showy perennial from five to seven feet high. Cauline leaves sessile, lanceolate, acute, glabrous. Flowers in terminal bracteate spikes, pale purple, spotted on the lower lip. A native of Texas, blooming in Autumn.
Ph. specidsa, from Siberia, has pink flowers; and Ph. Virgi-niana has lilac-purple or white flowers and linear-lanceolate leaves.