PYROLA 



gindsa, Gray, with pink or rose-colored fls. and subcor- 

 date to obovate, dull Ivs., occurs in swamps, Arctic 

 regions, and as far south as Ga., New Mex. ajid Calif. 

 Var. asarifdlia, Hook., with purple fls. and round kid- 

 ney-shaped to ovate-orbicular Ivs., occurs northward. 

 C. F. Wheeler. 

 FYROLA, One-flowered. Moneses grandiflora. 



Ft'EUS ( Latin name of pear tree ) . Sometimes spelled 

 Pints. Rosacea. Pome Fkuits. Flowers normally 

 perfect, regular, in spring; torus urn-shaped and at- 

 tached to the carpels and finally closing over them, and 

 with them becoming fleshy in fruit; calyx-lobes 5 and 

 persistent upon the top of the young fruit, or in some 

 cases falling away at partial maturity; petals 5, white or 

 red; stamens 20 or more; pistils 2 to 5, crowning a 

 2- to 5-loculed ovary in which the locules are usually 

 2-seeded. Fig. 2018. Pyrus is a polymorphous genus, 

 comprising some 30 to .iO species in the northern hemi- 

 sphere. Trees or shrubs, with alternate leaves which are 

 simple in the common species but compound in P. 

 heterophylla and rarely in some of the apple tribe. The 

 species are cultivated for their edible fruits and for 

 ornament. Apples and Pears are the leading species. 

 The species are mostly small trees, bearing clusters of 

 showy white or blush flowers with the leaves or in 

 advance of them. They are natives of the northern 

 hemisphere, mostly of oool temperate part.s, and the 

 greater part of them are hardy in the northern states. 

 They are of easy culture. The pear-like species may 

 be worked on Pear stocks, and the apple-like species on 

 Apple stocks. 



The fruit of Pyrus is of the kind known to botanists 

 as a pome. The morphology of the pome is still a sub- 

 ject of dispute, although most botanists now agree in 

 considering it to be a hollow torus (receptacle) in which 

 the ovary is imbedded. Fig. 2019 illustrates the theo- 

 retical structure. The ovary is at 6, wholly inclosed in 



ity like an apple, the flesh bearing grit cells; styles 

 usually free or not united at the base. (Nos. 1-5.) 



Of these plants there are perhaps 15 to 20 species, 

 natives ' —--u .„_..„, r- /, .„:„ _=.u .v. 



south-central Europe 



greatest expan 



region. 



(Flora 



ovule being a 



the fleshy torus a. Most of the edible part of the Apple 

 or Pear, therefore, is considered to be torus, whereas 

 the core is ovary. This ovary is of five carpels or cells, 

 as shown in the cross-section, Fig. 2020. It was formerly 

 held that the edible part is largely calyx -tube, but vari- 

 ous morphological considerations have inclined students 

 to regard it as stem rather than calyx. One of these 

 reasons is the fact that Apples sometimes bear a rudi- 

 mentary leaf (as in Fig. 2021), an organ 

 which is commonly borne only by stems. 

 There are the widest differences of 

 opiniou as to the generic limits of this 

 group of plants. What is regarded by 

 Benthara & Hooker as one genus is re- 

 garded by others as 10 or 12 genera ( see. 

 for example, E. Koehne, "Die Gattung 

 der Pomaceen," Wissensch. Beil. zum 

 Program des Palk-Realgymnasiums, Ber- 

 lin, 1890). In the present work, some of 

 these species (the quinces) are set off 

 as Cydonia, the medlar as Mespilus, 

 and the mountain ashes, chokeben-ies 

 and their kin as Sorbus. This restricts 

 Pyrus to the pear-like and apple-like 

 species. 



"EARS. — iPyrophoriim). Fruiteither 

 , conical base or possessing a cav- 



J019. 

 Diaeram of a 

 pome (pear). 

 .Showing the 

 torus part at a 

 and the ovary 



Of this particular region, Bossie 

 OrientalLs) reduces the species to eight, P. commwnis, 

 P. cordata, P. amygdaliformis, P. eJanyrifolia, P. 

 saUcUolia, P. Syriai-a, P. Boiu;ni<i. P. .jl.ihn,. Some 

 of these have fruits of comestiM.- valu.'. an. I it is not 

 impossible that they may be noiiljv .if aimli. .ration. 

 The best horticultural account ..f ili.- s|..-.i.> ..f Pears, 

 with particular reference to thtir pouiolojiical values, 

 will be found in vol. 1 of Decaisne's "Le Jardin 

 Fruitier du Museum," where superb plates are given. 

 2. Apples (Mains). — ¥m\t with a sunken base or 

 "cavity," the flesli withmit trrit cells; styles more 

 or less united \h'\..\\ -y.-. .i l:ii. 



IHciesof this sub- 

 ii.- common Apple, 

 I- in southwestern 

 ' .|.:in, several spe- 

 '-1 known are the 

 h small fruits that 

 ii Anierica is another 

 ai h.ii.l Crab, P. coro- 

 i I.. w leaved Crab, P. 

 .St. the Prairie States 

 lar wi-stern Crab, P. 

 1.1 g.iod characters to 

 separate the small-fruited Apples, particularly 

 the Asiatic forms. Carriere attempted to solve 

 thedifliculty {Pommiersmierocarpes, Paris, 1883) 

 by referring them all to one polymorphous species- 

 group. Mains microcarpa. Although Pyrus and Mains 

 are very closely related botanically, they hold their dis- 

 tinctions with much persistency and they do not inter- 

 hybridize. Many writers prefer to keep the genera dis- 

 tinct, but the characters of separation are too minute 

 and technical for ordinary di- 

 agnostic purposes. It does not 

 follow that characters have 

 generic value merely because 

 they are constant. The marks 

 that separate Mains from Py- 

 rus are not readily determin- 

 able on the herbarium sheet, 

 and are therefore of relatively 

 little value to the systeraatist, 

 for whom generic lines are 

 chiefly erected. Their distinct- 

 ness is further shown by their 

 relations to inter-grafting, al- 

 though the graftage-re" 



smooth-growiiiL' . 

 shed their call.-.- 

 set, represent.-, i I 

 naria of the Kasi 

 angustifolia of tin 

 Crab, P. loensis. 

 fusca. It 



cide 



vith the 



fication-relation. It is usually 

 impossible to graft the pear - species on the apple- 

 species with any degree of success ; yet pears thrive on 

 quinces and also on hawthorns, which are well marked 

 genera. 



