ipom] 



<£t)c ttoatfucg at Matmiy. 



626 



included stamens ; a two or three-celled 

 ovary with two ovules in each cell ; and 

 a slender style with a bilobed stigma, the 

 lobes capitate. 



Ipomcea is frequently cultivated as an 

 ornamental plant because of its showy 

 flowers, but it derives its chief importance 

 from the medicinal properties which many 

 of its species possess. These depend chiefly 

 on an acrid juice which abounds in their 

 roots, and which has a strongly purgative 

 quality arising from the presence of a 

 peculiar resin. Sometimes sugar and 

 starch replace the resin, and a valuable 

 edible root is obtained ; this is remarkably 

 the case in the allied genus Batatas, the 

 root of one species of which is the sweet 

 potato. Although the best jalap is obtained 

 from Exogonium purga, yet many species 

 of Ipomasa supply it, though of an inferior 

 quality. I. Turpeihum, a native of India 

 and the islands of the Pacific Ocean, is 

 employed by the natives as a common pur- 

 gative, and although the resin is more 

 diluted than in the true jalap, it is free 

 from the nauseous taste and smell of that 

 drug. The Mechameck of the North Ame- 

 rican Indians is I. pandurata. Its pow- 

 dered root acts like rhubarb, and has also 

 some reputation as a diuretic. The root 

 of the South American /. batatoides has 

 sufficient of the purgative resin to cause 

 it to be employed. Scammony, it is said, 

 can be obtained from /. tuberosa, the 

 Spanish Arbour Vine of Jamaica. I. sensi- 

 tiva is remarkable for the irritability of 

 its corolla. [W. C] 



IPOMOPSIS. A subgenus of Gilia, com- 

 prising those species which have alter- 

 nate divided leaves, flowers solitary or 

 somewhat clustered, and a corolla tube 

 very much longer than the calyx. See 

 Gilia. [C. A.J.J 



IRESINE. A genus of Amaranthacece, 

 natives of tropical and subtropical Ame- 

 rica (a single species reaching as far 

 north as Ohio), and also of Australia. They 

 are herbs with opposite stalked leaves, and 

 small scarious white flowers in lax pani- 

 cles, or dense heads, or spikes. The flowers 

 are often polygamous, or dioecious by abor- 

 tion. The fruit is a globular indehiscent 

 utricle. [J. T. S.] 



IRIARTEA. A genus of palms, from 

 which have recently been separated Socra- 

 tea, IriarteUa, Catoblastus, &c. The wax 

 palm (Ceroxylon), which has been combined 

 with it by some botanists, is here kept dis- 

 tinct. As now defined, Iriartea consists 

 of five species, one of which is a native of 

 Peru, and the others of the banks of the 

 Amazon river. All of them are tall-grow- 

 ing plants, some of them attaining a height 

 of sixty or eighty feet, or even higher, and 

 they are frequently elevated above the 

 conical mass of cylindrical roots, which 

 gives them a most remarkable appearance. 

 The stems are smooth, and marked with 

 distant circular scars, generally almost 

 cylindrical, but occasionally swollen or 

 bulged out towards the top. They bear a 



crown of large pinnate leaves, the lower 

 part of the stalks of which form a cylin- 

 drical sheath round the top of the stem ; 

 the leaflets are somewhat trapezoid in 

 form, and jagged on one side. The flower- 

 spikes are pendulous from below the leaves, 

 and have several spathes, the innermost 

 of which completely encloses them while 

 young, but eventually splits open ; both 

 sexes of flowers are borne on the same 

 spike. The fruit is roundish or egg-shaped, 

 and contains a single seed. 



I. exorrhiza, the Pashiuba or Paxiuba 

 palm of Brazil, is the tallest-growing spe- 

 cies, and its cone of roots is sometimes so 

 high that a man can stand in the centre, 

 with the tall tree above his head. These 

 aerial roots, being covered with little aspe- 

 rities, are commonly used by the Indians as 

 graters, whilst the hard outer wood of 

 the stem is employed for various portions 

 of their houses, and likewise exported to 

 the United States for making umbrella 

 handles. *-«. [A. S.] 



TRIARTELLA. A small South Ameri- 

 can palm, formerly called Iriartea setigera. 

 It differs greatly in general appearance 

 from the Iriarteas, which are all tall stout- 

 growing palms, whilst this seldom grows 

 higher than eighteen or twenty feet, and 

 has a perfectly straight cylindrical trunk 

 scarcely more than an inch thick. The 

 flowers also differ in the males having a 

 small rudimentary pistil in the centre of 

 the fifteen stamens, whilst the females 

 have no sterile stamens, containing only a 

 three-celled ovary. The Indians on the 

 Amazon and Rio Negro, where this palm 

 grows in the underwood of the forests, use 

 its slender stems for making their grava- 

 tanas, or blow-pipes, the weapon com- 

 monly employed by them in the pursuit of 

 game, and through which they blow small 

 poisoned arrows with unerring accuracy 

 and to a considerable distance. These 

 gravatanas are usually from eight to twelve 

 feet long, and have a bore of about a quar- 

 ter of an inch. The stems, being soft and 

 spongy in the centre, are easily bored by 

 pushing a rod of hard wood through them, 

 but in order to have the bore perfectly 

 smooth, the Indians prefer splitting them 

 in halves and carefully working a groove 

 in each half, afterwards neatly reuniting 

 and binding them round with the smooth 

 shining bark of a creeping plant. [A. S.] 



IRIDACEyE. (Ensatce, Irids.) A natural 

 order of monocotyledonous plants, belong- 

 ing to Lindley's narcissal alliance of Endo- 

 gens. Herbs with corms, rhizomes, or 

 fibrous roots, and mostly with equitant 

 leaves.and flowers in sheaths. Perianth six- 

 parted, in two rows, sometimes irregular ; 

 stamens three, inserted at the base of the 

 outer row of the perianth ; anthers innate, 

 opening on the back ; style dividing into 

 three petal-like portions, which bear the 

 stigmas. Capsular fruit three-celled, three- 

 valved, opening in a loculicidal manner ; 

 seeds with hard albumen. The plants are 

 found both in warm and temperate re- 

 gions ; they abound at the Cape of Good 



