PALIURUS ACULEATUS (_syn P. australis_).--Christ's Thorn, or Garden Thorn. Mediterranean region, 1596. A densely-branched, spiny shrub, with small leaves, and not very showy, yellowish-green flowers. It grows and flowers freely enough in light, peaty earth, but is not very hardy, the tips of the branches being usually killed back should the winter be at all severe.
PARROTIA PERSICA.--Persia, 1848. Well known for the lovely autumnal tints displayed by the foliage when dying off. But for the flowers, too, it is well worthy of culture, the crimson-tipped stamens of the male flowers being singularly beautiful and uncommon. In February it is no unusual sight to see on well-established plants whole branches that are profusely furnished with these showy flowers. For planting in a warm corner of a rather dry border it seems to be well suited; but it is perfectly hardy and free of growth when suited with soil and site. It is as yet rare in cultivation, but is sure, when better known and more widely disseminated, to become a general favourite with lovers of hardy shrubs.
PASSIFLORA CAERULEA.--Passion Flower. Brazil and Peru, 1699. Though not perfectly hardy, yet this handsome climbing plant, if cut down to the ground, usually shoots up freely again in the spring. The flowers, which are produced very freely, but particularly in maritime districts, vary from white to blue, and the prettily-fringed corona and centre of the flower render the whole peculiarly interesting and beautiful. P. caerulea Constance Elliott has greenish-white flowers; and P. caerulea Colvillei has white sepals and a blue fringe. The latter is of more robust growth, and more floriferous than the species.
PAULOWNIA IMPERIALIS.--Japan, 1840. This is a handsome, fast-growing tree, and one that is particularly valuable for its ample foliage, and distinct and showy flowers. Though perfectly hardy, in other respects it is unfortunate that the season at which the Paulownia flowers is so early that, unless the conditions are unusually favourable, the flower buds get destroyed by the frost. The tree grows to fully 40 feet high in this country, and is a grandly decorative object in its foliage alone, and for which, should the flowers never be produced, it is well worthy of cultivation. They are ovate-cordate, thickly covered with a grayish woolly tomentum, and often measure, but particularly in young and healthy trees, as much as 10 inches in length. The Foxglove-like flowers are purplish-violet and spotted, and borne in terminal panicles. They are sweetly-scented. When favourably situated, and in cool, sandy loam or peaty earth, the growth of the tree is very rapid, and when a tree has been cut over, the shoots sent out often exceed 6 feet in length in one season, and nearly 2 inches in diameter. There are many fine old trees throughout the country, and which testify to the general hardihood of the Paulownia.
