not cohering, finally fusiform; the limb campanulate, 5-lobed or 5-partite. Corolla often silky outside, funnel-shaped with an elongated tube; the lobes overlapping one another in the bud; throat of the tube bare. Stamens 5, inserted at the throat, of the corolla; filaments short; anthers short oblong, the theca; more or less extended or in some species setose at the base. Disk inconspicuous. Ovary fusiform, 2-celled; style exserted far beyond the tube of the corolla, ending in a clavate or capitate stigma. Ovules numerous, ascending, inserted on a placenta which is borne by the middle partition of the ovary. Fruit a septicidal, many-seeded capsule;, testa of the seeds extended at both ends into capillary appendages.

Uncaria is a close relative of the East Indian Nauclea, differing mainly in the characters of the fruit, which in the last-named genus is a capsule, not septicidal, but merely breaking up into two cocci or lobes. All the species of Uncaria are climbing shrubs found in the forested areas of the tropics. Over thirty species are known, most of them from' tropical Asia; two occur in South America and one in Africa.

Uncaria africana G. Don

Uncaria africana G. Don, 1834, 'General System of Gardening and Botany,' III, p. 471. Hooker, 1848, 'Icones Plantarum,' VIII, Pi. Dcclxxxi. Bentham, 1849, in Hooker, 'Niger Flora,' p. 381, Pi. Xlii. Hiern, 1877, in Oliver, 'Flora of Tropical Africa,' III, p. 41. Haviland, 1897, Journ. Linn. Soc. London, Botany, XXXIII, p. 76. E. De Wildeman And T. Durand, 1900, Bull. Herbier Boissier, (2) I, p. 25; 1901, 'Reliquia; Dewevreana;,' p. 106. fi. De Wildeman, 1903, 'Etudes Flore Bas- et Moyen-Congo,' I, p. 76; 1907, ibid., II, pp. 71 and 192. Th. And H. Durand, 1909, 'Sylloge Flor. Congol.,' p. 241. E. De WildeMan, 1910, 'Etudes Flore Bas- et Moyen-Congo,' III, pt. 2, p. 283; 1912, ibid., Ill, pt. 3, p. 484.

Nauclea africana Walpers, 1843, 'Repertorium Bot. Syst.,' II, p. 512 (nec Willdenow). Ourouparia africana Baillon, 1879, Bull. Soc. Linn. Paris, I, p. 228. K. Schumann,.

1891, in Engler and Prantl, 'Die Natilrl. Pflanzenfam.,' IV, pt. 4, p. 57. Hiern,.

1898,'Catalogue Afr. Plants Welwitsch,' II, p. 435. Uruparia africana K. Schumann, in Engler, 1895, 'Pflanzenwelt Ost-Afrikas,' C,

p. 378.

"A glabrous or sparingly pubescent shrub 4 to 40 ft. high. Leaves ovate-oval or lanceolate, acuminate, rounded at the base or nearly so, thinly coriaceous, with 5. to 7 lateral veins on each side of the midrib, shortly petiolate, 2 to 6 by 1 to 4 in.; stipules }{ to % in. long, usually bipartite with narrow partitions. Spines at first nearly straight, afterwards crooked. Flowering heads 1)ito 2 in. in diameter. Calyx tawny, as well as the corolla shortly and appressedly pilose-tomentose; limb shortly lobed. Corolla about % in. long, greenish yellow. Stamens glabrous; anther-cells obtusely produced at base. Fruiting heads 3 to 3% in. in diameter; pedicels % in. long; capsules % in. long. Tails of the seeds linear-setaceous, undivided at one end, bipartite at the other" (Hiern, 1877)

^aviland's diagnosis reads: "Frutex 1-15-metr. Hamuli glabri vel pubescentes; internodi 7-9 cm. Folia 13 cm. longa, 6 cm. lata, elliptico-lanceolata, longe acuminata, supra glabra, subtus glabrescentia, nervis 7-8. Petioli 7 mm. Stipulae bifida?, lobis acutis. Pedunculi 7 cm., maxime variabiles. Flores pedicellati vel subsessiles. Corolla sericea, mellea; tubus rem., lobi oblongi. Calyx sericeus; tubi pars superior 4 mm.; lobi 1 mm., obtuse triangulares. Stylus 18 mm.; stigma 4 mm., elongatoclavatum. Capsulae 2 cm., cum pedicellis a?quilonga-. Bractea? nulla?."

Sierra Leone, type locality (G. Don; Afzelius; Barter; Scott Elliot; Johnston).

Nigeria (Vogel).

Cameroon.

Spanish Guinea: Rio Muni (Mann).

Belgian Congo: Lower Congo; banks of the Lukungu Biver (Dewevre); Kisantu (Gillet); Inkisi Biver (Vanderyst). Kasai: Linkanda (Gentil). Upper Congo: Mondombe (Jespersen). Northeastern Congo forest: Mangbetu Country (Schweinfurth); Uele region (Seret); Barumbu (November 3, 1913; J. Bequaert; Col. No. 1069); Penge (January 27,1914; J. Bequaert; Coll. No. 2136); between Penge and

Irumu (village of Tete, February 22, 1914; J. Bequaert; Coll. No. 2658); between
Walikale and Lubutu on the Oso River (village of Mandiinbo, January 18, 1915; .1.
Bequaert; Coll. No. 6664).
Uganda.

Angola: Golungo Alto—"in the primitive forests of Sobato de Mussengue" and "in the very dense, primitive forest of Quibanga" (YVelwitsch). Also known from Madagascar and the Comoros.

Haviland distinguishes several varieties:

Variety (1). Flowers subsessile. Upper part of the calyx-tube 4 mm. long. Siena Leone, Niger, Mangbetu.

Variety (2) madagascariensis (Ourouparia madagascariensis Baillon, 1879, Bull. Soe. Linn. Paris, I, p. 228). Flowers subsessile. Upper part of the calyx-tube 2 mm. long. Malagasy Region.

Variety (3) angolensis Haviland. Flowers pedicellate. Upper part of the calyxtube 4 mm. long. Angola.

Variety (4). Flowers pedicellate. Upper part of the calyx-tube 2 mm. long. Cameroon.

The variety angolensis Haviland is described more in detail by Hiern (1898) as follows:

An arborescent shrub, glabrous except the inflorescence. Trunk in some cases more than 100 ft. long and 6 in. in the lower part, climbing to a very great height and then hanging down; branches patent, fuscous, rather glossy, tetragonal. Leaves opposite, elliptical, narrowly acuminate at the apex, obtusely narrowed or nearly rounded at the base, thinly coriaceous, glossy, dark green above, paler beneath, 2 to 4 % in. long, Yi to 1 % in. broad; lateral veins about 6 on each side of the midrib, slender; petiole % to )'\ in. long. Stipules ovate, small, somewhat hairy on the inner face, nearly deciduous. Spines axillary, mostly crooked, % to % in. long. Flower heads terminating the branches, shortly pedunculate, globose, about 2 in. in diameter. Flowers golden-tawny, about % to % in. long (including the exserted style), very numerous, crowded. Pedicels about % to }i in. long in flower, % in. long in fruit, tomentellous. Bracts 0. Calyx silky-tomentellous with short upward hairs, somewhat constricted above the ovary, greenish-fuscous; tube broader than the ovary, campanulate, funnel-shaped, % to % in. long, shortly 5-cleft, lobes thickly lanceolate. Corolla % to % in. long; tube slender, except the base clothed outside with downward tawny short silky-tomcntose hairs, % in. long; limb much broader than the tube, hemispherical, }{ to }{ in. in diameter, golden-tawny tomentose outside, glabrous inside, deeply 5-lobed; segments about % in. long, obovate-oblong, rounded at the apex with an apiculus. Stamens 5, about half as long as the corolla-lobes, glabrous, introrse, inserted on short, flattened filaments at the base of the corolla-limb. Ovary ellipsoidal, tomentose, rather thicker than the base of the calyx-limb, much thinner than the top of the calyx-limb. Style filiform, exserted about }i in. beyond the corolla, glabrous below, stigmatose and rather thickened in the upper part towards the clavate stigma. Young fruit subglabrous, about % in. long, % in. thick, narrowed at both ends especially towards the base.

This species probably occurs throughout the African Rain Forest. In a recent note, De Wildeman (1919) calls attention to the myrme

Fig. 91. Uncaria africana G. Don. Longitudinal section of myrmecodomatium at a node, showing three cavities communicating with one another; the aperture is not figured. Drawn from life at Barumbu, November, 1913; natural size.

cophytism of certain African plants of this genus. He proposes, provisionally, the varietal name myrmecophyta De Wildeman for specimens which I collected in the Ituri Forest at Penge and between Penge and Irumu, without, however, giving characters by which this new variety could be differentiated from the typical form. I am inclined to believe that myrmecophytism is normal for Uncaria africana throughout its range and has merely been overlooked thus far. When terminal branches alone are collected, there may be no indication of the peculiar myrmecodomatia in herbarium specimens, even should such have been present on lower parts of the plant. Ant-inhabited parts of plants are also frequently avoided by botanical collectors. Moreover, it is possible that the myrmecodomatia are absent or but little pronounced in certain individuals or at certain stages of growth.

Ecology Op Uncaria africana Here (Figs. 90 and 91) we have one of the many climbing bushes or "scramblers"—as Schimper proposed calling them—which frequently form tangles of vegetation over the low trees at the edge of clearings and along river banks. While the trunk and main branches are straight and stiff as in ordinary bushes, all or part of the lateral branches are limp and pliable. The latter either hang down freely or work their way upward, keeping hold of the other trees by means of the spirally curved hooks and woody thorns, which are placed in pairs above the nodes and are evidently modified branches. The leaves are glabrous, as well as the branches at the extremity of some of which the flowers or fruits form head-clusters.

The myrmecodomatium of this Uncaria consists of the enlarged and hollow basal internodes of two opposite, lateral branches, the cavities in this pair of swellings communicating with the hollow, very slightly swollen node of the main branch (Fig. 91). The middle chamber is more or less club-shaped, 5 to 6 cm. long and 10 to 20 mm. wide in the upper half; it is dug farther into the pith below than above. The two lateral cavities are 3 to 6 cm. long and 6 to 10 mm. broad.

All the specimens I had opportunity to study in the field were inhabited by ants of the genus Crematogaster, which were identified as C. excisa subspecies andrei (Forel) in the case of the plants found near the Oso River, between Walikale and Lubutu in January, 1915. The myrmecodomatia contained not only the queen, workers, and brood of the ants, but also numerous coccids. These scale insects were invariably located in the lateral swellings and fixed at the bottom of two deep, opposite, longitudinal grooves in the inner wall. One or more circular exit holes are pierced by the ants through the sides of the lateral cavities. Often the depressions occupied by the coccids are open to the exterior by means of irregular slits through which the ants enter and leave. It would thus seem that these grooves are gnawed by the ants, probably on account of some special hyperplasias formed in that region of the walls. The coccids merely select the grooves for nutritive, juicy tissue to be found there and continually renovated by the attacks of the ants.

On the plants examined by me at Barumbu in November, 1913, there were a number of young branches whose basal internodes, though distinctly swollen, were still filled with juicy pith tissue. In another instance, between Walikale and Lubutu, the basal swellings of many older branches were not yet inhabited by ants, presenting no exit holes; nevertheless, they were entirely hollow inside, so that the cavities of