OSTRYA.
OSTRYA CARPINIFOLIA (_syn O. vulgaris_).--Common Hop Hornbeam. South Europe, 1724. A much-branched, round-headed tree, with cordate-ovate, ac.u.minate leaves. Both this and the following species, by reason of the resemblance between their female catkins and those of the Hop, and between their leaves and those of the Hornbeam, have acquired the very descriptive name of Hop Hornbeam. This is a large-growing tree, specimens in various parts of the country ranging in height from 50 feet to 60 feet.
O. VIRGINICA.--Virginian Hop Hornbeam. Eastern United States, 1692.
Resembles the latter, but is of smaller growth, rarely exceeding 40 feet in height. They grow fairly well in almost any cla.s.s of soil, and on account of the long and showy catkins are well worthy of cultivation.
OXYDENDRUM.
OXYDENDRUM ARBOREUM (_syn Andromeda arborea_).--Sorrel-tree. Eastern United States, 1752. Unfortunately this species is not often found under cultivation, being unsuitable generally for our climate. In some instances, however, it has done well, a specimen in the Knap Hill Nursery, Surrey, being 30 feet high, and with a dense rounded head. The flowers are very beautiful, being of a waxy white, and produced abundantly. It wants a free rich soil, and not too exposed site.
OZOTHAMNUS.
OZOTHAMNUS ROSMARINIFOLIUS.--Australia, 1827. A pretty little Australian Composite, forming a dense, twiggy shrub, with narrow, Rosemary-like leaves, and small, whitish, Aster-like flowers which resemble those of its near relative, the Olearia, and are produced so thickly that the plant looks like a sheet of white when the blooms are fully developed.
It flowers in June and July. In most parts of the country it will require protection, but can be cla.s.sed as fairly hardy. Cuttings root freely if placed in sandy soil in a cool frame.
PAEONIA.
PAEONIA MOUTAN.--Moutan Paeony, or Chinese Tree Paeony. China and j.a.pan, 1789. A beautiful shrubby species introduced from China about one hundred years ago. The first of the kind introduced to England had single flowers, and the plant is figured in Andrews" _Botanists"
Repository_ (tab. 463) under the name of P. papaveracea. The flowers are white with a dark red centre. In the _Botanical Magazine_ (tab. 2175), the same plant is figured under the name of P. Moutan var. papaveracea.
This is perfectly hardy in our gardens, and is the parent of many beautiful and distinct varieties, including double and single white, pink, crimson, purple, and striped.
PALIURUS.
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.
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.
Pa.s.sIFLORA.
Pa.s.sIFLORA CAERULEA.--Pa.s.sion 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.
PAULOWNIA IMPERIALIS.--j.a.pan, 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.
PERIPLOCA.
PERIPLOCA GRAECA.--Poison Vine. South Eastern Europe, and Orient, 1597.
A tall, climbing shrub, with small, ovate-lanceolate leaves, and cl.u.s.ters of curious purplish-brown, green-tipped flowers produced in summer. The long, incurved appendages, in the shape of a crown, and placed so as to protect the style and anthers, render the flowers of peculiar interest. Though often used as a greenhouse plant, it is perfectly hardy, and makes a neat, deciduous wall or arch covering, thriving to perfection in rich soil that is well-drained. It is readily propagated from cuttings.
PERNETTYA.
PERNETTYA MUCRONATA (_syn Arbutus mucronata_).--p.r.i.c.kly Heath. Magellan, 1828. This is a dwarf-growing, wiry shrub, with narrow, stiff leaves, and bears an abundance of white, bell-shaped flowers. It is a capital wind screen, and may be used to advantage on the exposed side of rockwork or flower beds, or as an ornamental shrub by the pond or lake side. The small dark-green leaves, the tiny white flowers, and great abundance of deep purple berries in winter, are all points that are in favour of the shrub for extended cultivation. The pretty, pinky shoots, too, help to make the plant attractive even in mid-winter. Propagation by layers or seed is readily brought about. To grow this shrub to perfection, peaty soil or decayed vegetable matter will be found most suitable. There is a narrow-leaved form named P. mucronata angustifolia, and another on which the name of P. mucronata speciosa has been bestowed.
There are many beautiful-berried forms of the Pernettya, but as their flowers are small can hardly be included in our list.
PHILADELPHUS.
PHILADELPHUS CORONARIUS.--Mock Orange, or Syringa. South Europe, 1596. A well-known and valuable garden shrub, of from 6 feet to 10 feet high, with ovate and serrulated leaves, and pretty racemes of white or yellowish-white, fragrant flowers. P. coronarius aureo-variegatus is one of the numerous forms of this shrub, having brightly-tinted, golden foliage, but the flowers are in no way superior to those of the parent.
It is, if only for the foliage, an extremely pretty and distinct variety. P. coronarius argenteo-variegatus has silvery-tinted leaves; P.
coronarius flore-pleno, full double flowers; and P. coronarius Keteleeri flore-pleno is the best double-flowered form in cultivation.
P. GORDONIa.n.u.s, an American species (1839), is a well-known and beautiful shrub, in which the flowers are usually double the size of those of the common species, and which are not produced till July, while those of P. coronarius appear in early May.
P. GRANDIFLORUS (_syns P. floribundus, P. latifolius_ and _P.
speciosus_).--Southern United States, 1811. This has rotundate, irregularly-toothed leaves, and large white, sweetly-scented flowers produced in cl.u.s.ters. This forms a stout bush 10 feet high, and as much through. There are two varieties, P. grandiflorus laxus, and P.
grandiflorus speciosissimus, both distinct and pretty kinds.
P. HIRSUTUS.--North America, 1820. Another handsome, small-flowered species, of dwarf growth, and having hairy leaves.
P. INODOROUS, also from North America (1738), differs little in size and shape of flowers from P. grandiflorus, but the flowers are without scent. The leaves, too, are quite glabrous and obscurely toothed.
P. LEMOINEI BOULE D"ARGENT is a cross, raised in 1888, from P. Lemoinei and the double-flowered form of P. coronarius. The flowers are double white and with the pleasant, but not heavy, scent of P. microphyllus. P.
Lemoinei Gerbe de Neige bears pleasantly-scented flowers that are as large as those of the well-known P. speciosissimus. There is an erect form of P. Lemoinei named erectus that is also worthy of note.
P. LEWISI, from North America, is hardly sufficiently distinct from some of the others to warrant special notice.
P. MICROPHYLLUS, from New Mexico (1883), is of low growth, and remarkable for its slender branches, small, Myrtle-like leaves, and abundance of small, white flowers. It is a decidedly pretty shrub, but is not so hardy as the others.
P. SATZUMI (_syn P. chinensis_).--j.a.pan, 1851. A slender-growing species, with long and narrow leaves, and large, white flowers.
P. TRIFLORUS and P. MEXICa.n.u.s are other species that might be worthy of including in a representative collection of these plants.
This is a valuable genus of shrubs, all being remarkable for the abundance of white, and usually sweet-scented, flowers which they produce. They require no special treatment, few soils, if at all free and rich, coming amiss to them; while even as shrubs for shady situations they are not to be despised. Propagation is effected by means of cuttings, which root freely if placed in sandy soil.
PHILLYREA.
P. ANGUSTIFOLIA (narrow-leaved Phillyrea), P. ilicifolia (Holly-leaved Phillyrea), P. salicifolia (Willow-leaved Phillyrea), P. buxifolia (Box-leaved Phillyrea), and P. ligustrifolia (Privet-leaved Phillyrea), are all more or less valuable species, and their names indicate their peculiarities of leaf.a.ge. P. angustifolia rosmarinifolia (_syn P.
neapolitana_) is a somewhat rare shrub, but one that is well worthy of culture, if only for its neat habit and tiny little Rosemary-like leaves. It is from Italy, and known under the synonym of _P.
rosmarinifolia_.
P. LATIFOLIA (_syn P. obliqua_).--Broad-leaved Phillyrea. South Europe, 1597. This is a compact-growing and exceedingly ornamental shrub, with bright and shining, ovate-serrulated leaves. For its handsome, evergreen foliage and compact habit of growth it is, perhaps, most to be valued, for the small flowers are at their best both dull and inconspicuous. Not very hardy unless in the sea-coast garden.
P. MEDIA (_syns P. ligustrifolia_ and _P. oleaefolia_).--South Europe, 1597. This is another interesting species, but not at all common in cultivation.