620 



GARDENERS' MAGAZINE. 



September 24, 1898. 



ERE 



ROBUSTUS. 



This stately hardy plant is yearly becoming more popular, and each 

 season larger numbers of towering spikes are seen in gardens and 

 nurseries The species was discovered in Turkestan, and first flowered 

 in the Botanic Gardens of St Petersburg and Moscow in 1873, when Dr. 

 Regel named and described it. The flowers vary slightly in colour, but 

 are usually of a pale rose or peach shade ; they measure two inches 

 across and many scores of them are produced on one well developed 

 spike 'in the Rectory Gardens, Scole, Norfolk, the Rev. F. Page-Roberts 

 grows this plant finely, as the illustration, from a photograph kindly sent 

 by him, will show. 



Mr Page-Roberts writes :— " The tallest spike in the picture of 

 Eremurus robustus was eleven feet six inches, and the shortest nine feet 

 six inches. The four plants were put in their present position after 

 their seed had ripened at the beginning of August last year, a decisive 

 rotation of those who sav they ought not to be disturbed. Indeed, 



Eremdrus robustos at Scole Rectory. 



those which were not moved last year have not developed so remarkably. 

 The difficulty is not in the cultivation, for this is simple enough, but in 

 procuring good matured plants, eight years old at the least. All that is 

 needful for the successful growing of these majestic, beautiful hardy 

 plants to perfection is a rich light loam (I have, unfortunately, no good 

 loam in my garden to experiment with), a sunny position, well sheltered 

 from strong winds, which damage the leaves, an occasional dose of 

 liquid manure, and protection from frost in the spring, when the leaves 

 begin to expand and disclose the soft flower spikes. Water getting into 

 them and freezing, cripples them. No protection is needed in the winter." 



with the fine qualit. 

 stock of the old Pet 



From their first introduction I have beem familiar 

 es ot two good tomatos : Polegate, probably the very best 

 fection put into commerce; and Golden Jubilee, the very 



ruited yellows. I •>■. k,,.i. ti>». ,.ori<>tipc growing recently 



come I h Z ' L° g B , tan u ly ' 1 cannot but wonder whence finer crops are to 

 House Jar^ns S !"2fe since » tall, narrow span house at Regent 

 I y ?Uow Si, ** ain ' roitin 8 very finely, and still tall, vertical plants. 



(^W«JuS fr, ThT m the markets . then it would be difficult to excel 



richer cilourcd or £L EST'- c ^\'y no one could have handsomer, 



bury i„ w iZ^Z tha h T than Pole ** te g ave - Mr - Ta y lor » at Tcwkes - 



of fruit e£h 2 \ l h ' S plants would yield him from ten to twelve pounds 



HOMOLOGY OF PLANTS. 



By Professor F. O. Bower, D.Sc, F.R.S. 



( Continued from page 602. ) 



Homology. 



But various writers admit in varying degree this factor of comparison 

 as controlling other considerations. There is indeed a wide range of 

 difference on this point. I will cite only two extreme views. On the one 

 hand is the view of Strasburger, which he enunciated so early as 1872. 

 The enthusiasm for evolution in the Jena school found its botanical ex- 

 pression in the aphorism, " The highest problem of morphology is to 

 explain the form of plants, but this problem can only be solved genea- 

 logically." This statement is repeated in a more definite form in Stras- 

 burger's text-book : " Phylogeny is thus the only real basis for mor- 

 phology." 



At the other extreme is the method of physiological organography put 

 forward by Sachs in his lectures. I am aware that he subsequently 

 modified his views ; I merely quote the system which he propounded in 

 1882, as being the antithesis to that of Strasburger. For in the physio- 

 logical organography descent is hardly taken into account at all ; parts 

 which are plainly of distinct origin by descent are classed together. This 

 organography of Sachs, though introduced with all its author's charm of 

 style, never convinced the botanical world, for it treated plants too much 

 as the creatures of present circumstance. It may be taken as illustrating 

 the extreme reactionary swing of the pendulum from the non-physiological 

 attitude of the formal morphologists ; a protest against the exclusion of 

 function from the morphological arena. The protest was salutary, but its 

 form was extravagant. 



Let us now consider whither "phylogeny, as the only real basis of 

 morphology," may lead us. Let us take as our provisional view that 

 homology in the strictest sense implies repetition of individual parts, in 

 successive generations, just as the hand of the child repeats in position 

 and qualities the hand of the mother. Though among seed-bearing 

 plants, for instance, this repetition may apply for the plant-body as a 

 whole, it will be at once apparent that such repetition as regards the 

 individual is found in comparatively few cases in plants. The continued 

 embryology of all the higher forms, the indefinite number of the parts 

 successively produced, and the variety in detail of their arrangement show 

 that in the strictest sense repetition of individual parts cannot be traced. 

 In a pan of seedlings of the sunflower, raised from seed of the same 

 parent, the cotyledons in all cases may be regarded as homologus in the 

 strictest sense, as they correspond in origin, number, position, and form 

 to like parts in the parent. In a similar way the first root of the seedling 

 appears to be individually identical with the first root of the parent, or of 

 any other seedling of the batch. In those plants in which a foot or 

 suspensor is present occupying a constant position with regard to the 

 parts of the embryo, it will not be doubted that within near lines of 

 affinity the foot in anyone specimen corresponds to that of any other. 

 The exact repetition which is thus found to exist may be regarded as the 

 most complete type of homology. 



Starting from this repetition of individual parts in plants nearly 

 related, there is a divergence by gradual steps in two directions— firstly, 

 in the individual plant, where the later formed parts may assume forms 

 and positions which may even raise a question of their essential c< ^r e ' 

 spondence. Thus, in the batch of sunflower seedlings, there may be a 

 varying number of leaves, with varying transition from the decussate to 

 the alternate arrangement, intervening between the cotyledons and the 

 capitulum. As they vary in number and position, these cannot, in the 

 strictest sense, be accepted as individually comparable each to each oy 

 descent— the lineal representatives of like individual parts in the parent. 

 The lateral roots also, though essentially similar, do not correspond eacn 

 to each, either in number or in position. . . 



Again, to go a step further, a fern prothallus produces anthendia _am 

 archegonia ; their number and position are not uniform ; by conai ^ 1 n:> 

 of culture we have them under control, and can induce anthendia om>, 

 or we can induce a formation of archegonia upon the upper surra , 

 where they are usually absent. Plainly these cannot be held seve rai > 

 the exact representatives of like individual parts in a previous 

 tion. Another exceptional, but most interesting, case is that ot /i^j 

 anomalum, Hk. and Am., which Sir William Hooker remarks is possi > 

 an abnormal form of Aspidium (Polyst.) aculeatum. Svt. J* /J" 5 

 the sori, instead of being all on the lower surface, as in allied 1 ern . 

 often upon the upper surface of the leaf. There is no sign of ^riio 

 explain the anomaly, while the sori themselves present no . s n l ? isiurn 

 peculiarity except that they are sometimes quite destitute ot inu 

 There has doubtless been a transfer of developmental capability xr 

 the usual position of the sori to the anomalous one. In case ^ 

 transfers as these, we do not doubt that the parts in q uest ' 0 ^ tenip iate 

 ranked as comp S rable to those in the normal position ; wc ^'j; nC e f 

 here, as in the case of the sunflower leaves, an essential c °[ res P thus 

 but not an individual repetition of the parts, and we learn that pa 

 essentially corresponding to one another may be transferred 10 u 

 positions. h are le* 5 



Secondly, in plants more or less nearly related, those ™icn ^ 

 akin may show so slight a similarity in detail that again q uestl0 ^ rclc5 of 

 essential corresponce of the parts may arise. Within nca ^ r • ^ 

 affinity these questions will affect only the appendage^ of minor 



n ?L-in the degree 



correspondence of the larger members may become 



x^«ui inbiance, the three great pnyia 01 ">»'6 ■ - as a whole m 

 1 erns , Eqmseta, and Lycopods. While the if^f^t^ that of 

 each of these maybe accepted as homologous by descent f thc 



the others, the question as to the true correspondence by aw 



