408 



THE DICTIONARY OF GARDENING, 



Seed continued. 



they come into contact, and, by their union, form a tissue 

 that quite resembles those formed by ordinary cell- 

 divisions, and that does itself increase in size in this 

 way. The endosperm, also called the albumen, is formed 

 in all Seeds ; but in many it disappears, as it is used up 

 in the growth of the embryo, e.g., in the Seed of an Apple, 

 or of a Bean. Such Seeds are called " exalbuminous." 

 In many Seeds a considerable, or even a large, albumen 

 exists in the ripe Seed, with the embryo lying in it (Poly- 

 gonum), or around it (Lychnis), or at the base (Carex), 

 or on one side of it (Grasses). Besides the endosperm, 

 another form of albumen, known as "perisperm," occurs 

 in many plants. This is formed in the tissue of the 

 nucleus, outside the embryo-sac. Perisperm is less 

 common than endosperm, but co-exists with the latter in 

 the ripe Seeds of a few plants (Nymphtea), and occasionally 

 replaces it (Canna). The albumen may contain starch, 

 oil, cellulose, or other materials for nourishment of 

 the young plant; and its texture varies accordingly. 

 The presence and nature of the albumen afford important 

 characteristics of Natural Orders. Under Ovule, it was 

 pointed out that the form of the ovule might remain 

 orthotropons, or might become campylotropons or ana- 

 tropous. The ripe Seeds show corresponding differences 

 in form. 



Seeds generally possess two coats, the outer called 

 " testa," and the inner " tegmen." The latter is usually 

 thin and membranous. The testa is very often thick 

 and hard, e.g. in Brazil Nuts. It often bears outgrowths 

 in the form of warts or ridges, hairs (Cotton), or wings, 

 which are sometimes of large size (Pinus, Bignonia). 

 All these outgrowths bear reference to the modes of 

 distribution of Seeds, fitting them to adhere to the bodies 

 of birds or quadrupeds, or to be distributed by wind. 

 Occasionally, the testa has an outer layer of cells, which 

 become mucilaginous on contact with water, and cause 

 Seeds, when moist, to adhere to the bodies of animals. 

 On the outer surface of the testa is the hilum, or scar, 

 indicating the point of attachment of the Seed to its stalk. 

 Many Seeds possess what resembles a third coat when 

 ripe. In some, this coat, the "arillus," grows up from 

 the placenta around the Seed ; in others, it grows from 

 the micropyle downwards, and it is then distinguished as 

 the " arillode." An outgrowth is often seen in anatropous 

 ovules (e.g., in Violets) over the t'unicnlus (the adherent 

 stalk) ; it is called a " caruncle." This third coat, whether 

 arillus, arillode, or caruncle, in some Seeds is fleshy 

 (e.g., mace of Nutmeg), serving as an inducement to 

 animals to swallow the Seeds, and thus to secure wide 

 distribution in their excrements ; in others, it forms 

 a tuft of hairs, and serves as a float for the Seed. In 

 size and form, Seeds vary greatly in different plants, 

 from the minute, dust-like Seeds of Orchids to the large 

 Seed of the Cocoannt. The number produced by different 

 plants is also very variable ; but into these and similiar 

 matters it is not possible to enter here. 



SEED-BEDS. A term applied to narrow strips of 

 land prepared for the raising of seedling plants that are 

 intended for transplanting into their permanent quarters, 

 instead of being sown and allowed to grow there from 

 the first. In all cases it is advisable to select a position 

 for Seed-beds where the soil is friable and in good work- 

 ing order, and to render the surface smooth and fine 

 before scattering the seeds over it. It is an easy matter 

 to mark off any requisite width, according to the quantity 

 of seed to be sown. 



SEED-SOWING. See Propagation. 

 SEEMANNIA (named after Berthold Seemann, 

 1825-1871, a botanist and traveller). ORD. Gesneraceae. 

 A monotypic genus. The species is a strigose-pubes- 

 cent, stove, perennial herb, with a creeping rhizome 

 closely allied to Achimenes and Isoloma. For culture 

 see Gcsuera. 



Seemannia continued. 



S. Benaryl (Benary's). A synonym of S. silvatiea. 

 S. silvattca (sylvan), fl. of a bright scarlet, on solitary, axillary 



pedicels ; calyx with an adnate tube and five narrow lobes ; 



corolla tube nhortly gibbons at base, the liinb of very short, 



erecto-patent lobes ; stamens affixed to the base of the corolla. 



Winter. L three or four in a whorl, very shortly petiolate, often 



canescent beneath ; upper ones gradually reduced to bracts. 



h. 3ft. to 4ft. Peru, SYNS. S. IleiMryi (II. G. 814), tf. tcrnifolia 



(R. G. 126). 

 S. tcrnifolia (ternate-leaved). A synonym of S. siloatica. 



SEGMENT. One of the divisions into which a leaf 

 or other flat organ may be cut. 



SEGO. A common name for Calochortus Nuttallii, 



SEGREGATE. Separated. The reverse of Aggre- 

 gate. 



SEIiAGINE2B. A natural order of shrubs, nnder- 

 shrubs, or annual or perennial herbs, inhabiting extra- 

 tropical regions, Australia excepted. Flowers white, blue, 

 or rarely yellow, rather small, hermaphrodite, irregular, 

 bracteate, ebracteolate, in dense, globose, oblong, or elon- 

 gated, terminal or very rarely axillary spikes ; calyx 

 live-cleft or five-parted, or, owing to some of the parts 

 being connate or deficient, three-parted, two-parted, or 

 spathaceous ; corolla gamopetalous, shortly or slenderly 

 tubular at base; limb four or five-lobed, one or two- 

 lipped, or sub-regular, spreading ; stamens four, didyna- 

 mous, or two. Fruit small, indehiscent. Leaves alter- 

 nate, or the lower ones rarely opposite or radical, entire 

 or toothed. The order comprises eight genera and about 

 140 species. Examples : Globularia, Hebenstretia, Selago. 



SELAGINELIiA (diminutive of Selago, the old name 

 for another Lycopod). ORD. Lycopodiacece. A vast genus 

 (upwards of 300 species) of stove, greenhouse, or hardy, 

 evergreen plants, much resembling Mosses. "The genus 

 is concentrated in the tropical zone, and has its head- 

 quarters in tropical America. Only two species extend 

 their range into Europe ; and the Selaginellas of the Cape, 

 temperate Australia, and South temperate America, are 



neither numerous nor remarkable Habit entirely 



of Lycopodium, from which it differs by its dimorphic 

 spores and sporangia, some of the species, small and 

 fugacious, resembling Hepaticae, with not more than two 

 vascular bundles on the main stems. Stems copiously 

 branched, the ultimate branching usually flabellate- 

 dichotomous, trailing, sub-erect, sarmentoso, or scandent, 

 with the root-fibres confined to the base, or in the trailing 

 species extended to the upper nodes ; in shape more or 

 less distinctly quadrangular, the faces angled (stems 

 goniotropous, Spring) or the faces flat (stems pleuro- 

 tropous, Spring) ; nodes sometimes distinctly articulated. 

 Leaves email, furnished only with a single central vein, 

 usually tetrastichous and dimorphous, and more or less 

 oblique, the two rows of the lower plane larger and 

 more spreading, the two rows of the upper ascending, 

 adpressed to the stem and imbricated; in the sub-genus 

 Euselaginella multifarious, or, if tetrastichous, all alike. 

 Spikes usually tetrastichous and often sharply square, 

 but in two sub-genera dimorphic on the same plan as 

 the leaves, but mostly resupinate (i.e., the small bracts 

 on the same plane as the large leaves, and vice versti) " 

 (J. G. Baker, to whose admirable monograph of Selagi- 

 nella, in the "Journal of Botany," 1883-5, we are in- 

 debted for the appended descriptions of the species 

 best known to cultivation in this country). Selaginellas 

 grow freely in any light soU, which should be kept open 

 by intermixing charcoal, or small potsherds, through it. 

 They require to be kept quite moist at all times, and 

 prefer shade. Propagated readily from cuttings, made 

 from the creeping stems, which emit roots at nearly every 

 joint. 8. Kraussiana is the well-known Lycopod so useful 

 for edgings to greenhouse beds, and for decorative pur- 

 poses in pots. This may be propagated in quantity at 

 any season. Cuttings for preserving a collection of the 



