PONGAMIA 



to Piscidia but differs from it by having t'he pods short, 

 compressed, smooth, and 1-seeded instead of elongated, 

 winged, and several-seeded. 



pinnata, W. F. Wight (Cytisus pinnata. Linn P. 

 glabra, Vent. Pongam pinnata, Wight. Galedupa 

 indica Lam.). A tall erect tree or climber, with glabrous 

 branches and Ivs.: Ifts. 5-7, opposite, subcoriaceous, 

 oblong or ovate, pointed, stalked, 2-4 in. long: fls. in 

 a simple peduncled axillary raceme, nearly as long as 

 the Ivs.; pedicels 2-4 joined together, M-M"*- long. 

 with a pair of minute bractlets in the middle; corolla 

 J^in. long, standard silky on the back: pod woody, 

 glabrous, l A~ l Ain. thick, 1% in- l n g> with a . sh ^ 

 decurved point. Intro, into U. S. in 1910. Suitable 

 as an ornamental in the southern states. The ash of the 

 wood is used for dyeing. The seed yields a thick red- 

 brown oil used for illuminating and medicinal purposes. 

 The foliage is bright and very handsome. The tree 

 sometimes reaches a height of 40 ft. Grown in S. Calif. 



P. L. RlCKEK. 



PONTEDERIA (G. Pontedera was an Italian botan- 

 ist, 1688-1757). Pontederiacese. Perennial herbs of 

 bogs and ponds with strong horizontal rootstocks, 

 frequently used in water-gardens, and for naturalizing 

 in wet places. 



Leaves long-petioled, ropt-lvs. with a sheathing 

 stipule within the petiole: infl. a 1-lvd. st. bearing a 

 spike of violet-blue ephemeral fls.; perianth funnel- 

 form, 2-lipped, the 3 upper segms. united to form the 

 3-lobed upper lip, the 3 lower spreading and clawed; 

 stamens 6 ; ovary 3-celled, 2 of the cells empty. Two 

 or 3 species from N. and S. Amer. 



Pontederias are well worth cultivation in bog-gardens 

 and shallow ponds, and P. cordata is offered by dealers 

 in native plants. It thrives best in water 10 to 12 inches 

 deep. It transplants with ease. Propagated mostly 

 by division. It grows as far north as Nova Scotia and 

 Minnesota, and therefore is perfectly hardy in all 

 parts of the country. 



cordata, Linn. PICKEREL- WEED. Growing in clumps: 

 Ivs. heart-shaped, blunt, from a spathe-like bract: 

 upper lobe of perianth marked with a pah- of yellow 

 spots (rarely all white) ; calyx-tube in fr. crested with 

 6-toothed ridges. Nova Scotia to Ont., Minn., and 

 Texas. B.M. 1156. Mn. 7:1. V. 2:196; 3:336. G.C. 

 III. 52:466. Var. lancif&lia, Morong (P. lancifolia, 

 Muhl. P. lanceolata, Nutt.), differs from the type in 

 having lanceolate Ivs. N. Amer. B.M. 8108. 



For P. crdssipes. Mart., see Eichhornia crassipes. Vol. II, p. 1105. 

 P. montendensis, Hort., has appeared in the foreign journals but 

 its botanical characters are unknown. G.W. 3, p. 619. 



F. TRACY HUBBARD. 



PONTHIEVA (named in honor of M. de Ponthieu). 

 Orchidacese. Terrestrial, glabrous or pilose herbs which 

 are not in common cultivation, though sometimes grown 

 in gardens. 



Roots fascicled in a short rhizome: Ivs. subradical, 

 ovate or lanceolate, membranaceous, more or less 

 petioled: infl. a lax raceme borne on a simple elongated 

 scape; the pedicels often glandular-pubescent: fls. 

 medium-sized; sepals free, spreading; petals adnate to 

 the column, narrower than the sepals; labellum adnate 

 to the base of the column by a claw, ascending, with 

 the lateral lobes winged; column short or rather long, 

 terete, apex broadened: caps, oblong, erect, beakless. 

 About 30 species, Trop. and Subtrop. Amer. 



glandulSsa, R. Br. Plants 1-1 % ft- high, with lanceo- 

 late-elliptical, pointed and short -petioled Ivs. which are 

 3-5 in. long: raceme 3-6 in. long; fls. green or greenish 

 brown; outer sepal ovate-oblong, lateral ones flat; 

 petals half -cordate-deltoid; labellum abruptly dilated 

 above the claw, roundish with a terminal, linear appen- 

 dage. W. Indies and S. Amer. B.M. 842 (as Neottia 

 glandulosa). Formerly offered by a dealer in native 

 plants. Probably not hardy N. F. TRACY HUBBARD. 



POPULUS 



2753 



POPCORN: Corn. 



POPLAR: Populus. P., Yellow: Liriodendron. 



POPPY: Papaver. California P.: Eschscholtzia. Celandine P.: 

 Stylophorum. Corn P. : Papaver Rhoeas. Horned P. : Glaucium. 

 Opium P.: Papaver somniferum. Prickly P.: Argemone. Shirley 

 P.: an improved strain of Papaver Rhceas. Tulip P.: Hunnemannia. 

 Welsh. P. : Meconopsis cambrica. 



POPULUS (ancient Latin name, of disputed origin). 

 Salicacese. POPLAR. ASPEN. COTTONWOOD. Soft- 

 wooded trees of rapid growth, some kinds of which are 

 much planted on roadsides and in grounds, particularly 

 when quick results are desired. 



The poplars are dioecious, with both staminate and 

 pistillate flowers naked but from a cup-shaped disk, 

 and in slender mostly drooping precocious catkins in 

 which the subtending scales are toothed, cut or cleft at 

 the apex: stamens few or many, usually numerous, on 

 distinct filaments: pistillate fls. with mostly a single 

 1-loculed mostly sessile ovary with short style and 2-4 

 often lobed long stigmas: fr. a small 2-4-valved caps., 

 containing cottony seeds, the mature catkin sometimes 

 with a necklace-like or moniliform character: Ivs. 

 alternate, stalked, mostly broad: buds scaly 2 often 

 resinous. Species probably about 35-40, in the 

 northern hemisphere, mostly extra-tropical, although 

 very many more than this have been described, some 

 of them being hybrids. The poplar of lumbermen is 

 the tulip tree. (See Liriodendron.) 



Botanically the poplars comprise a most bewildering 

 group, and there is wide divergence of opinion and prac- 

 tice as to the limits and names of species. Many of the 

 cultivated forms are assumed to be hybrids, but the 

 origin of most of them, so far as parentage is con- 

 cerned, can be little more than conjectured. It is 

 likely that seedlings of some of these hybrids break 

 up into forms much resembling the parents, and thereby 

 still further contribute to the bewilderment. The 

 trees being dioecious, the herbarium specimens may 

 not represent both sexes; as the catkins appear in 

 advance of the foliage, the specimens may not repre- 

 sent the same plant or type; the foliage is very various, 

 sometimes even on the same tree, and specimens are 

 likely to be taken from the lower part of large trees 

 where the leaves are small or from the terminal shoots 

 of young trees on which the leaves are large and have a 

 different character. Of some kinds only one sex is 

 known. The habit of growth is also very characteristic 

 even in species or forms on which the foliage is very 

 similar, but this character is of course not represented 

 in botanical specimens. It will be seen, therefore, 

 that the usual herbarium collection may not have full 

 value hi the determination of species. There is natu- 

 rally a tendency to place great stress on leaf-forms in 

 the description of species, even though hi some groups 

 practically the whole range of forms may be found on 

 single trees. These difficulties are particularly marked 

 hi this country hi the P. deltoides-angidata group. 

 With regard to the variability of the leaves of Popu- 

 lus, Schneider writes in "Plants W'ilsonianae," "it is 

 helpful to keep the following in mind. L. A. Dode 

 was the first who clearly described the variation of 

 the leaves according to the age of the plants, the 

 position of the branches, and the climatic and other 

 conditions under which they were produced. ... I 

 think it sufficient if we distinguish three different 

 kinds of leaves: (1) the leaves of the offshoots or suckers 

 (folia turionum radicalium) ; (2) the leaves of the normal 

 but not the vigorous shoots of the young plants (folia 

 ramorum [sed non turionum] plants juvenilis); and 

 (3) the leaves of the old trees (folia arboris adultae 

 fructiferae) . The leaves of the third land we usually find 

 at the ends of vigorous branches of young plants when 

 they are growing well and becoming mature. If we 

 compare leaves of different species it is necessary to be 

 very careful only to compare the same kinds of leaves. 



