simple inflorescence 



TERATOLOGY 



mon on conifers (especially Abies) anil some deciduous 

 trees. Similar deformations are sometimes due to in- 

 sect agency, or to unknown causes. For example, a 

 • develop flower-clusters instead 

 of single flowers, e.g., in the 

 common plantain. 



3. Proliferution is continued 

 growth of the axis or the de- 

 velopment of a branch from 

 growing points which usually 

 either do not form or remain 

 dormant. For example, the 

 growing point of the axis of the 

 flower is usually obliterated in 

 the formation of the )>istil. but 

 in the pear, uppli- ;inil >ir:iw- 

 berry it fre.|i"i"Iy '■"iiiiiiucs 

 its growth thi'Mmii ih.- iImw-.t 

 and may even 1.. rLin.- ;i l.afy 

 shoot beyond the fruit. Pro- 

 feration may also occur by 

 the continued growth of the 

 axis through a compact flower- 

 cluster, like the head of Com- 



^ posit£e; or by the development 



added of branches in the axils of the 

 petals and sepals, e. g., in cauli- 



TERATOLOGY 



1783 



2481. Anothf 



of polycarpy. 

 In this ea 

 oence may 



e cousidered 

 of the 

 of growth with 

 whorl of carpel: 



flower, or the rose shown in 

 Fig. 2482. Some double flowers are made "extra dou- 

 ble" by this sort of proliferation. Proliferation is said 

 to occur in almond embryos, one or more smaller 

 embryos arising from the normal one ; but the state- 

 ment lacks confirmation and such an origin is highly im- 

 probable. When proliferous branches show a tendency 

 to separate easily and to develop roots, or when they 

 become bulb-like, so that they reproduce the plant read- 

 ily when separated, the plant is said to be viviparous. 



4. By various causes complete noH-development of 

 organs (.suppression) may occur; or an organ may be 

 arrested at any stage of its growth or be dwarfed. 

 Correspondingly, extraordinary growth of any part 

 (hypertrophy) is common. Arre;St or suppression is 

 often ascribed to the influence of other organs, but 

 these alleged causes are in few cases supported by ex- 

 perimental evidence. Thus, it is commonly believed 

 that the absence of seeds in the banana and pineapple 

 is due to the excessive development of the flesh in 

 these fruits, but this is a mere conjecture as yet. Some- 

 times spurs and nectarines do not develop. Pigs. 2486-7. 



II. Alteration op Form, involving no considerable 

 change in nature or function of the organs. 



1. Fascintion in stems (Fig. 2483) produces a broad- 

 ened and fluted form, often curved in crozier-like fash- 

 ion. The apex is furnished with several buds (rarely 



only one), and the arrangement of the leaves is quite 

 anomalous. Fasciation is especially common in rapidly 

 growing stems when an abundant supply of both water 

 and food is available. Asparagus, dandelion and 

 sucker shoots arising from trees after topping or se- 

 vere pruning, frequently furnish examples. Although 

 the fasciated stem seems to have been formed by the 

 early union of several stems, this is rarely the case; 

 rather the growing apex develops extraordinarily in 

 one (transverse) dimension or organizes several buds 

 which grow in unison. 



2. Longitudinal growlli in stem parts which normally 

 remain short leads to the unusual separation of the 

 leaves. This is especially noticeable when the floral 

 leaves become thereby more or 

 less widely separated. This is 

 likely to be accompanied by 

 transformation of the floral into 

 green leaves, and sometimes b> 

 proliferation. 



3. Unequal growth lengthwist 

 produces apparently twisted 

 stems, with irregular displace 

 ment of the leaves. Such dis 

 placement is especially notice 

 able when it affects whorled 

 leaves, the whorls being 

 stretched out into irregular spi 

 rals. Unequal growth in two di 

 mensions by the tissues of a 

 leaf produces the "curly" oi 

 crispate leaves, characteristic 

 of manv cultivated plants. Fig 

 12G7, Vol. 2. 



4. Local deformities, such as 

 swellings, tubercles and galK 

 of various forms, are usualh 

 due directly to the presence of 

 a plant or animal parasite 

 Fungi, either inhabiting the 

 particular region deformed, or 

 more widely spread through the 

 plant but forming eproductive 

 bodies at the seat of the swell 

 ing, occasion excessive growth 

 of some or all of the tissues 

 The "black-knot " on cherry and 

 plum trees, the "plum pockets 

 the tubercles on the roots of 

 clovers, peas and their kin, are 

 a few out of the hosts of de 

 forraities of this kind, due to 

 plant parasites, and known by 

 various names. 



Many insects, either in the 

 cdurse of feeding on plant 

 juices, or by laying eggs on or 

 in plants, or by reason of the 

 temporary occupation of the 

 part by the larval insect, bring 

 about the formation of galls of 

 various kinds on leaves, stem, oi 

 tions produced are of the most varied shapes. Someth 

 they are merely the production of an unusual number 

 of hairs of special form; sometimes a leaf bulges out 

 at one spot to form a deep pocket or pouch; sometimes 

 the blade of a leaf is rolled or folded, with or without 

 thickening; all degrees of thickening or outgrowths 

 are produced, from a slight tumor to a perfectly globu- 

 lar apple-gall or even a cylindrical tube-gall; sometimes 

 a bud has the number of its scales greatly increased to 

 form a cone-like gall; or a flower is distorted until its 

 nature is almost unrecognizable. The variety of form 

 is almost as various as the insects and plants concerned. 

 Indeed, the same insect at different stages of its de- 

 velopment may produce galls of different sorts on the 

 same plant. All orders of true insects except the 

 Orthoptera and Neuroptera may produce galls, but by 

 far the larger number are due to the gall-flies and saw- 

 flies of the order Hymenoptera. The gall-apples of the 

 oaks, the prickly galls of the rose, the irregular brown 

 swellings on canes of the blackberry, and the smooth 

 gall-apples of the willow leaves and twigs are well- 



• roots. The malforma- 



