JiLY, 1902.] 



KNOWLEDGE 



163 



without a correspomling chantre iu the soft parts, so that 

 piiiuu; aud pinnules are densely imbricate and overlapping. 



Fig. 2. — Blechnum Spicant^ var. /rinerrium, from the ifourne 

 Mountains. One-third natural size. 



and a frond which to judge from the stoutness of its stipe 

 or stem ought to be a foot or two in length is crowded 

 into a length of six inches. 



E. — Truncation. — An abrupt suppression of certain 

 parts of the frond is not uncommon, and sometimes 

 produces remarkable effects. In many cases a ragged and 

 iHiattraetive form is the result, but ou the other haud two 

 of the most interesting of all wild finds belong to this 

 class. These arc the varieties VirtoriK and Frizellix of 

 the Lady Feni, lioth of which have been already referred to. 

 Victorias, a single plant found iu Scotland, is a cruciate- 

 crested variety. In this Fern each pinna is aborted just 



^Z' 



4 .-^i^ 



Fig. 3. — Athyrium Filix-fiemina, var. VictorUe. 

 Half natural size. 



Ixn'ond the first pair of pinnules. The latter have con- 

 secjueutly the wliole burden of food-pnjduction, by means 

 of assimilation, thrown u^ion them, and to get tbeamount 

 of green surface requisite for this duty these basal pinnules 

 have been enlarged and sub-divided till they almost equal 

 pinnse in size, and st.aud out at a wide angle to one 

 another, crossing at right angles those above and below 

 them. The subdivisions of these enlarged pinnules are 

 themselves frequently aborted and cruciate in a similar 

 manner. But in addition, the tips of the pinnae and frond 



Fro. 4. —Athi)rium 

 Filix-ftemina, var. 

 Frizellire. Top of 

 frond. Half natural 



bear an elegant form of cresting ; so that we are lost in 

 wonder as to how this beautifully symmetrical multiple 

 variety can have originated in nature. 

 This cruciate character (Latin : crit- 

 ciatiis, crossed) is known iu other forms 

 of Lady Fern, and in Pobjstichum 

 angtilare and other species, but its com- 

 bination in the wild state with crestinir 

 is unique. A. F.-f. FrizeUi.-ixs-.xuoihiT 

 of the most remarkable of natural 

 varieties. In this, the secondary rachis, 

 or midrib of the pinna, aborts at or 

 near the second pair of pinnules ; the 

 tertiary rachis aborts also, so that 

 instead of a normal pinna we get a 

 tiny rosette of densely crowded and 

 overlapping pinnviles, themselves con- 

 gested and rounded. The result is not 

 easy to describe, but its appearance is 

 shown in Fig. .5. Curiously enough, in 

 spite of all the crowding, the pinnules 

 remain copiously fertile, and have 

 yielded an abundant offspring. In 

 the Hart's-tongue the truncate char- 

 acter appears in a curious manner. The shortened midrib 

 rises out of the surface, aud forms a stiff horn, which often 

 overtops the abruptly rounded termination of tlie lamina. 



F. — Twisting. —This character sometimes produces 

 forms whicli might fairly be called monstrous, such as 

 VSLT. flexuosnm of PolysticJuim angulare, in which the mid- 

 rib twists so much that the upper half of the frond is 

 frequently reduced to an inextricable ball. But in other 

 cases the result is more interesting. In var. recolveni', 

 for instance, of which excellent examples have been found 

 both in P. angulare and L. FiUx-mas, the pinnaj cun-e 

 uniformly backwards till they meet behind, forming the 

 fronds into arching tubes. The name var. reflexiim is 

 usually a|>plied when it is the pinnules that curve back- 

 wards. Sometimes this is done so completely that the 

 pinnie form perfect tubes ; more often the pinnule is bent 

 liackwards both transversely and longitudinally — a 

 common character in the Lady Fern, for instance, when 

 growing in strong light. 



Gr. — Incre.vse of Soft Pakts. — Into this class come a 

 lai-ge number of the most remarkable and most beautiful 

 varieties. While the first stages of development in this 

 direction consist of foliose or very leafy forms, its full 

 development is reached in the plnmosmn type. Here a 

 great expansion of the divisions of the lamina occurs, 

 accompanied by a papery texture and generally by com- 

 plete barrenness. This type may, indeed, in many ways 

 be considered analagous to double flowers, since in both 

 the production of the sexual generation — the stamens and 

 pistil iu one case, the spore and subsequent prothallium in 

 the other — is sacrificed to leafy growth. The plumose 

 character is found in many of our Perns. It is iu the Lady 

 Pern that it attains its most remarkable development, 

 providing a number of forms of glorious beautv, charac- 

 terized by a wealth of finely-cut delicate foliage. In the 

 Common Polypody the plumose form is represented by the 

 well-known var. cambricum, a very leafy divided form. 

 In the Hart's-tongue, the leafy development produces the 

 complicated overlapping frilling which characterizes the 

 crispam forms. A most interesting variety which comes 

 also into class Gr is var. pulcherrimiim of P. amjulare ; in 

 this the pinnules are prolonged, and, as recently discovered 

 (see p. 115), frequently develop prothallia at their tips. 

 Indeed, the greater number of the known oases of apospory 

 occur in varieties of this leafy class, belonging to the 

 genera Polysticimm, Athyrium, and Scolopendrium. 



