356 



HENDERSON'S HANDBOOK OF PLANTS 



PSI 



work, varj'ing greatly with age and conditions 

 of growth in density and quality. The bark 

 is valuable in tanning leather. A large num- 

 ber of sports, forms, or seedling variations are 

 grown under distinctive names. 



Psi'dium. Guava. Derived from psidion, the 

 Greek name of Pomegranate. Nat. Ord. Myr- 

 tacece.. 



An extensive genus of low-growing ever- 

 green trees, confined chieflj' to the "West In- 

 dies and South America. They are much es- 

 teemed for their fruit. P. Guaiava, produces 

 the well-known Guava fruits, so largely em- 

 ployed in the preparation of jellies, a staple 

 article of West Indian commerce. The fruit 

 is small, yellow, not unlike an Orleans Plum. 

 It is juicy, and in flavor somewhat resembles 

 a Strawberry. P. Cattleyanum, the Purple 

 Guava, though originally brought to Europe 

 from China, is most probably a native of Bra- 

 zil. The fruits, which are produced in great 

 abundance, and are readily distinguished 

 from the common Guavas by their deep, 

 claret-colored, pitted rind, are filled with a 

 juicy, pale flesh of a very agreeable acid- 

 sweet flavor. 



Psilosa'nthus. A synonym of Liatris. 



Psilo'tum. From psilos, naked ; the plants are 

 almost destitute of leaves. Nat. Ord. Lyco- 

 podiacecB. 



A genus of Club-mosses, containing numer- 

 ous forms, reducible, however, to two species. 

 P. trifiuetrum grows on the trunks of trees in 

 tropical or equable climates, and extends 

 through Brazil and Central America to the 

 southern United States. It bears cultivation 

 well, and is not uncommon in green-houses. 

 The spores burst when placed in water, and 

 emit a cloud of microscopic particles. 



Psora'lea. From psoraleos, warted or scurfy ; in 

 reference to the plants being for the most 

 part sprinkled all over, or roughened with 

 glandular dots or wart-like points. Nat. Ord. 

 LeguminofiCB. 



A large genus consisting of nearly one 

 hundred species of annual and perennial 

 herbs, and shrubs, found in great abundance 

 at the Cape of Good Hope and America, more 

 sparingly in Asia, northern Africa and Aus- 

 tralia. The leaves of P. glandulosa, are used 

 in Chili as a substitute for tea, under the 

 name of "Jesuits' Tea." P. esculenta, is a 

 native of Wisconsin, Missouri, and other 

 parts of the Northwest, where its tuberous 

 roots, known as Indian or Prairie Turnips 

 (Pomme Blanche, and Pomme de Prairie, of 

 the Yoyageurs), form part of the food of the 

 indigenous population. It is a roughish, hairy 

 plant, with roundish heads of blue flowers. 

 Some of the Cape species are shrubs, and are 

 in cultivation in green- houses. 



Psycho'tria. From psyche, life ; refemng to 

 the powerful medicinal qualities possessed by 

 several of the species. Nat. Ord. RubiacecF.. 



A large genus comprising about five hun- 

 red species of shrubs or small trees, erect, 

 climbing, or twining, found in tropical coun- 

 tries, especially in America. The flowers are 

 generally unattractive, but P. Jasminoides, 

 known better as Gloneria, forms a beautiful 

 green-house plant, covered, when in bloom, 

 with terminal, corymbose panicles of snowy- 

 white tubular flowers. P. Chontalensis, and P. 



PTE 



cyanococca, are both very ornamental green- 

 house plants, bearing clusters of deep blue 

 berries (often thirty to sixty on a bunch), very 

 useful as decorative plants in winter. They 

 are both natives of Nicaragua, introduced in 

 1870, and are propagated by cuttings or seeds. 



Pta'rmica. A genus now included under 

 Achillea. 



Pte'lea. Shrubby Trefoil. Hop-tree. The 

 Greek name of the Elm, here applied to a 

 genus with similar fruit. Nat. Ord. Rutacece. 

 P. trifoliata, our native species, is a small 

 tree, ten to fifteen feet high, with trifoliate 

 leaves, and clustered greenish flowers, fol- 

 lowed by curious winged seed-vessels. The 

 leaves and fruit, when bruised, emit a strong 

 odor of hops, whence the popular name. 

 When properly trained, this species makes a 

 very interesting lawn-tree. 



Pteli'dium. So named by Thomas from its 

 similarity to Ptelea. Nat. Oi'd. Celastracece. 



P. ovatum, the only described species, is an 

 ornamental green-house shrub, with opposite, 

 coriaceous, ovate leaves and terminal cymes 

 of light-green flowers. It was introduced 

 from Madagascar in 1818, and is propagated 

 by cuttings of the ripened wood. 



Pteridology. That branch of botany which 

 relates to the study of Ferns. 



Pte'ris. Brake. From pleron, a wing; the 

 shape of the fronds or leaves. Nat. Ord. 

 Polypodiaceoe. 



A very extensive genus of Ferns, widely 

 distributed over the temperate and tropical 

 regions, and differing as widely in character. 

 Many of the species are highly valued for 

 green-house and house decoration, as well as 

 for cutting to use with cut flowers. P. serriu- 

 lata and its crested varieties ; P. cretica, and 

 especially its variegated form, P. c. albo-lineata, 

 P. tremida, P. scnberida, P. argida, and many 

 others, are all invaluable to the florist, and 

 are grown in immense numbers near all our 

 large cities. P. quadriaurifa, var. argyrcm, 

 forms a noh)le specimen and is one of the most 

 valued Ferns for green-house decoration. P. 

 aspericaulis, var. tricolor, is a very attractive 

 sort, but requiring more heat and moisture 

 than many other kinds, is seldom seen in 

 good form. P. aquilina, is the common Brake 

 or Bracken. 



Pteroca'rpus. From pteron, a wing and karpos, 

 a fruit ; the pods are girded by a broad wing. 

 Nat. Ord. LegnminoscB. 



A genus of trees inhabiting the tropical 

 parts of Asia, Africa, and America. They bear 

 generally loose panicles of yellow flowers, 

 rarely violet or white, and are often very 

 showy. The genus comprises about fifteen 

 species, of which a few are in cultivation. 

 Gum Kino is obtained from various trees of 

 this genus. P Indicus, furnishes the Burmese 

 Rosewood, and P. santnlimts, yields the deep 

 red dye-wood known as Red Saunders, large 

 quantities of which are annually exported 

 from India. 



Pteroca'rya. From pteron, a wing, and caryon, 

 a nut ; winged fruit. Nat. Ord. Juglandacem. 



A small genus of very ornamental, low- 

 growing trees, inhabiting China, Japan and 

 the Caucasus. P.Caucasica, has pinnate leaves, 

 and small flowers, which are borne in catkins, 

 and are succeeded by winged seed-vessels. In 



