V 



426 



THE GARDENERS' MAGAZINE. 



June 8, 1912. 



VIVIPAROUS FERNS. 



In a general way, most of t4he plants of 

 higher organisation are viviparous in the 

 sense that the buds seated in the axils of 

 the leaves are really individuals, capahle 

 of self-development if removed from their 

 place of origin and installed under condi- 

 tions enabling them to form roots, or, as 

 in grafting, to obtain nourishment other- 

 wise. The term^ however, is usually applied 

 to cases where young plants appear as out- 

 growths on sites not usually occupied by 

 buds, as in the case of Asplenium bulbi- 

 ferum, the fronds of which develop a pro- 

 fusion of youngsters which break out from 

 the actual surfaces of the subdivisions, and 

 often attain a size w'liile still 



which permits them to Dear a 

 generation. This is an extreme case, and 

 as a familiar illustration can hardly be ex- 

 celled. Many of its nearly related species 

 do the same thing, and it has 'been xe- 

 miairked th)at, being this ^endlowed witili 

 extra reproductive power in this direction, 

 the spores, though abundantly produced, 

 rarely yield plants. 



This viviparous character in its latent 

 form is much more common among ferns 

 than flowering plants, but in the- latter 

 we have it, nevertheless, in various types, 

 the strawberry, for instance, and any simi- 

 lar stoloniferous grower, is practically vivi- 

 parous in so far that it bears well-defined 

 youngsters at the nodes of its stolons prior 

 to their rooting, and in such cases as 

 Sedum soboliferum, we see a quite different 

 type, its little globular offspring being fur- 

 nished with a root or two, and then sent 

 rolling in aJI directions to establish them- 

 selves on their own account. 



Returning to ferns, which, as we have 

 said, present this phenomenon more fre- 

 quently than other plants, we find many 

 examples of viviparousness pure and simple, 

 eome specific and some varietal. Thus 

 among the Woodwardias, W. radicans 

 bears one or more young plants near the 

 end of each frond, and these grow and 

 develop actual roots until their weight 

 brings them in contact with the soil, and 

 enables them to root therein and take a 

 start for fresh strides, a gigantic imitation 

 of the tiny so-called Walking Fern (Camp- 

 tosorus rhizoohvUus), which 



attached, 

 bear a second 



eisely si 

 however. 



rhizophyllus), 

 ilar. Woodward 

 has its fronds 



acts pre- 

 orientalis, 

 favourable 



situations 



little 



m 



1 iterally covered w it h 

 plants produced from surface buds, and 

 so lightly attached as to be easily 

 rubbed off, when they fall parachute 

 fashion to the ground, and so obtain 

 their chance of an independent career. 

 Many of the Shield feme (polystichum) 



^ _ jss profusion in 



the axils of their sub-divisions, these under 

 natural conditions being home to the 

 ground when the frond has run its seasonal 

 course, and decays a-t the base. A con- 

 siderable number of varieties of this family, 

 not reputedly viviparous, yet bear one or 

 more such 'bulbils in the axils of the two 

 lowermost pinnae. Several forms of Las- 

 trea montana do the like, L. m. Barnesi 

 and L. m. folifera, to wit, two rare forms. 

 An elongated type of Asplenium fontanum 

 known as Asplenium f. refractum bears 

 similar bulbils. C^stopteris bulbifera has 

 a fashion of its own of producing fat, 

 fleshy, bi-lobed bodies, as hig as peas in the 

 axils of its fronds, and these when shed, 

 give rise to strong plants wherever they 

 fall, rendering tlie fern a veritable weed. 



In all these cases and many analogous 

 ones which could be cited, the bulbils spring 

 either from the axils of the frond divisions, 

 in which case they are practically identical 

 with ordinary buds of the phanerogams, or 



from the upper surfaces as viviparous out- 

 growths proper, but, in rarer cases, as in 

 l>astrea vivipara, we find these bulbil plants 

 originating on the under surfaces of the 

 fronds in conjunction with the spore heaps 

 presumably from modified sporangia. This 

 description of ibulbil is also found on 

 several of our plumose varieties of Athyrum 

 felix foemina, on forms of Adiantnm capillus 



FOUR NEW 

 RHODODENDRONS. 



During the present century a large num- 

 ber of new rhododendrons have been intro- 

 troducecl to European gardens from vari- 

 ous parts of China, and some of these are 

 now sufl^ciently well establisheil to blossom 

 veneris, A, c- v. daphnites, and imbricatum, freely enough for us to form an idea of 



Polypod 



simum. In all these cases, the bulbils 

 spring from the sites of the sori, and are 

 frequently associated with perfect sporan- 

 gia and spores- In the primary phase of 

 fern life, the prothallus stage, we find also 

 a type of viviparousness, or rather two, 

 since the prothallus fern formed from the 

 spore very frequently buds out at the edges, 

 or even from the surface, into other pro- ago 



I.e. 



thalli, and where apogamy occurs, it is tfie 

 prothallus which buds out into a fern pro- 

 per by means of a simple asexual bulbil 

 precisely akin to those formed upon the 

 fronds, and finally we get the converse 

 form of viviparousness when the fronds in 

 the aposporous ferns develop prothalli from 

 these tips. 



These various forms of viviparousness 

 are, in most cases, immense aids to the cul- 

 tivator, since under proper treatment the 

 plants so produced root readily, and form 

 specimens far more quickly than if raised 

 from spores, months being saved in the 

 operation, J^'urthermore in valuable plants, 



whose spores are apt to yield varied 

 progeny, the bulbils may he fairly relied 

 upon to reproduce truly. We say fairly, be- 

 cause instances have certainly occurred 

 where bulbil plants have developed into 

 very different types This, as ibud 'sports 

 are not uncommon, is only to be expected, 

 seeing that if a tendency to vary is in the 

 blood, so to speak, we may as reasonably 

 expect it to evidence itself in the mother- 

 cell of a bud as in that of a sporangium or 

 single spore. Nevertheless, it may be taken 

 as a fact that selective culture, with a view 

 to improvement of type is far less likely to 

 reap results if bulbils be employed than 

 if spores be sown, the sexual interaction on 

 resulting prothalli undoubtedly being a 

 factor in variations 



Thus, to revert to our illustration of vivi- 

 parousness in Asplenium bulbiferum, this 

 fern must have been raised by millions by 

 trade hands on account of its facile culture 

 and marketability, but generation after 

 generation originating from bulbils only, 

 not a single variety worthy of the name 

 has made its appearance, while we do not 

 think that any fern raised on a like scale 

 from its spores, can be quoted as equally 

 constant. 



Ordinary bulbil growths are, as we have 

 said, easy to raise; but the extraordinary 

 ones associated with the spore heaps are, 

 with the exception of Lastrea vivipara, by 

 no means easy to establish. For one reason, 

 they only make their appearance right at 

 the fag-end of the growing season as a sort 

 of final effort at growth, and hence have 

 a great tendency to perish with the fronds. 

 We have succeeded several times in pull- 

 ing a smaller percentage through by 

 severing the small pieces of frond on which 

 they are situated, and inserting these in 

 sterilised soil, so that the bulbils just touch 

 the soil, by keeping them close and giving 

 them a little warmth, the strongest manage 

 to retain vitality through the winter, and 

 to form roots the following spring, when, 

 of, course, they are safe. The smaller the 

 portion of attached frond the better, and 

 this is sure to decay and in so doing will 

 too frequently infect iis tiny offspring with 

 fatal germs. 



Cha9. T. Dbueby, V.M.H., F.L.S. 



their value as garden plants. The four 

 species to which allusion is made w^ere all 

 introduced by Messrs. J. Veitch and Sons 

 Chelsea, though the me<:lium of their col- 

 lector, Mr. E. H. Wilson. All are of com- 

 paratively dwarf habit^ comparing in height 

 with the two Chinese species, R. yuniian- 

 ense and R. rubiginosum, w^iich were 

 brought to public notice about twenty years 



All appear to be as hardy as those 



severe 



two species, which stand the winter well, 

 but sometimes have their flowers or young 

 shoots cut hy a late and rather 

 spring frost. 



R. ambignum forms a bush two feet or 

 more high, w ith ovate leaves, the larger ones 

 being two to two and a-half inches long. 

 The upper surface is green, the under 

 glaucous, spotted with small brown scales. 

 From four to six flowers^ each about one 

 and a-lialf inches across, are Ixirne in 

 clusters from the points of the branches. 

 The colour is yellow, but the upper petal 

 is heavily spotted with green. Evergreen 

 rhododendrons with yellow flowei*s are not 

 very common, therefore this is of special 

 interest. 



R. augustini is conspitcuous by reason of 

 the large size of its flowers, for they bear 

 comparison w^ith those of large-groAving 

 garden hybrids. Plants a couple of feet 

 high may be seen growing in companion- 

 ship with the previously-mentionetl species 

 in the vicinity of King William's Temple at 

 Kew, The bushes in question are about 

 two feethigh^ and bear lanceolate or oblong 

 leaves up to two and a-half inches long, and 

 one inch wide. Tlie stalks are about a 

 quarter of an inch long, and together with 

 the mid-ribs and bark of the younger 

 branches, intensely hairy. From four to 

 six lilac, orange-spotted flowers are borne 

 together in fairly compact heads, each 

 flower being two inches across. This spe- 

 cies was described in 1890 in Vol. XXVI. 

 of the Journal of the Linnean Society, 

 from specimens collected by Mr. A. Henry 

 in the Patung District of Hupeh. 



R. concinnum differs from the others by 

 having bright, reddish-purple flowers, each 

 one to one 'and a-half inch across, in 

 small clusters, the upper petal being 

 marked with reddish-brow^n spots. 

 ovate leaves are one and a-half to two 

 inches long, the larger ones being about 

 three-quarters of an inch wide, gieen 

 above and glaucous beneath, both surfaces 

 being covered with small brow^n scales. 



R. siderophyllum l^ears a resemblance to 

 11. yunnanense, especially when in flower, toi 

 the blooms are of a similar size and shape, 

 but flesh-coloured and spotted with yellow- 

 ish-brown. The leaves are narrow, one to 

 two inches long, and up to three-quarters 

 of an inch wide. Of loose habit, this spe- 

 cies has a less inviting appearance than tne 

 others, though it will probably become niore 

 vigorous as its requirements become n^t 

 known. , 



These and the numerous other new rnv 

 dodendrons from the same country are we 

 worth the attention of garden lovers, a 

 though with a genus which contains ^"^^^ 

 large number of good garden shriibs 

 rhododendron, they will have an uphill ngi 

 if they are to oust the more beautitm^ 

 the older kinds from the foremost piac*^ 

 they now occupy. W. Dallimobe- 



