PRENANTHES 



DrainHKe is necessary in all pots over 4-meh anil tor 

 harii-wODileil plants even tliat size is better drained. 

 Tliis is tecbuically called "cracking," i. e., placing pots- 

 liiTils in the bottom of the pot to allow the quick pas- 

 sage of water and admit air to the roots. Place a large 

 piece over the hole in the bottom of the pot and the 

 remainder in smaller pieces. There are usually enough 

 broken pots around a place to supply the needs. Char- 

 coal is an excellent material for supplying pot drainage, 

 none better. An inch or so of drainage is sutJicinnt in 

 a 5- or tj-inch pot, two inches or so for all sizes ;iI.oM' 

 these. A bottom of broken stone, cinders or gra\i-I is 

 essential upon which to stand the pots, as such a stratum 

 accelerates drainage, while at the same time providint; 

 a moist surface so beneficial to plants in a greenhouse. 



A few words of caution may not be out of place 

 before closing this branch of the subject. Never shift 



well 



ith 



these days such plants will brini; .noui;!! m thi' best 

 markets to pay for the space ami iimiiI.1i' I'l.r 2- and 

 3-inch pots use sifted soil, but f'n- 1 inrli aiii! i.\-.'r soil 

 well broken, but having plenty of til.i r from ^.d in it, 

 should be used. Always water plants thoroughly after 

 shifting so as to soak the soil to the bottom, and do not 

 water again until they show dryness half way down the 

 pot on the outside. Patrick O'Mara. 



POURRETIA. SeePiiya. 



POURTHIfflA villosa. See Pkotinia. 



PRAIRIE CLOVER. Petalostemon. 



PRAIRIE DOCK. SUphhim terebinthinaceum. 



1947. Too high. 



plants while the ball of soil is wet; it should be dry 

 enough to crumble readily to the touch. Never shift 

 iTito dirty pots: it will pay to clean them, especially the 

 inside. Never shift a pot-bound plant without looisen- 

 ing the soil on the surface of the ball. A few smart 

 raps with the closed fist will do it; or better still repot 

 as now described. 



Repotting is necessary freriucntly wlicn plants have 

 become pot-bound, or when fnun :mi\ ho . ih. y appear 

 to require it; .such, for instum . ii..ni over- 



shifting, over-watering or im . kind. In 



such cases the soil should li. ii i in ilie roots 



almost entirelv and the plant pin mii. a |,mi a sizo or 

 two smaller than it has been t,'io« jri- in. lakiri- .■■•nv to 



firm till- soil well, and it a slin.l.l.v plant pnim- it 1 k 



according to its needs and .■oo.iifmn. Shade such 

 plants until danger of wiltim.' i- i.a^i ami waiir spar- 

 ingly until new and vigoroii- l;i -h a, : .ir, showing 

 that the subjects have regain. i .| health. 



There are a few cultural d.t associated 



with potting which may with pr >r,i 1.. a.ided as a 

 closing paragraph. The high, narrow pot shown on 

 the extreme right of the line of pots in Pig. 1937 is fre- 

 quently used for roses and palms by some, especially 

 tor Cocos iVechlelliana, which makes a long tap-root 

 and which it is almost invariably fatal to break. It is 

 feasible, however, to avoid this if the seeds are sown 

 in 6-inch pots, using 4 inches of clinkers as a bottom. 

 These check the downward growth and induce develop- 

 ment of fibrous roots in the soil, so that tin- tap-root 



niav be cut off below them an.l tl ilmaT v i' inch pot 



usi-d with safety. It is not n. i ,. Iliedocp 



pot f..r roses in anv case. I'l la . m .cd the 



diaim'tiT i>f the pot should l... -i . n i i.. allow for 



develoipinent. The best market growers ]dunge the 

 pots in soil to half their depth, as it is necessary in the 

 spring months because of the rapid evaporation of 

 water. This refirs especially to geraniums, fuchsias, 

 heliotropes, p. tiiiiia = . rt.-. Care must be taken, how*- 

 ever, to lift th.in ...-.■a-innally .so as to prevent the roots 

 from gettiiiL' lahl in ih.- -..il through the hole in the 

 bottom of th.- i...t. r.-ii inches apart from center to 

 center fi>r su.li |.laiit- will not be too much if stocky 





fc??. ^n) V' 



1948. Pot too full. 



PKENANTHES (Greek words, meaning drooping 

 blossom). UompdsiUe. Rattlesnake Root. A genus 

 of about 16 species of tall perennial herbs, of which 10 

 are natives of North America, A f^'w sj„.,.iis are ofTered 

 by collectors. Prenanthes are hau i.iiiin..l plants 

 with dull colored heads borne m : i i! . ■ tiainal 

 panicles. Lvs. alternate, lower ..n. i iL'ittate, 



cordate, often much divided: ujip. i mi nulato and 



much narrower and smaller heads: ri-:ii)-lld. • akenes 

 terete, 4-5-angled, usually striate. The species are ex- 

 tremely variable. They are of easy culture in any good 

 soil. 



A. Involucre glabrous. 



B. lleftih'< 5~l-fUl.: involucre very narrow, onli/ 1 line 



thick. 



altissima, Linn. A variable species. Stem 3-7 ft., 

 slender: fls. greenish yellow; pappus straw-colored or 

 whitish. July-Oct. In open or shade, Canada to Ga. 

 and Tenn. 



BB. Heads 8-16-fld.: involucre broader, 1%-S lines 

 thick. 

 c. Pappus deep cinnamon-broirn. 

 41ba, Linn. Stem 2-5 ft. high, usually purplish: In- 

 florescence thyrsoid-paniculate: fls. dull white. Aug., 

 .Sept. Open woods and sandy soil, Canada to Ga. and 

 111. B.B. 3:289. Mn. 3:161. 



cc. Pappus straw-colored. 



serptntaria, Pursh (iVdbalus Frdzeri, DC). Stem 

 usually about 2-4 ft. high, sometimes purple spotted; 

 lis, purjilish, greenish white or yellowish. Julv-Oct. 

 Ont. to Fla. and Ky. B.B. 3:289. 



