

AN ENCYCLOPAEDIA OF HORTICULTURE. 



77 



Pergnlaria continued. 



soft, downy, 4in, long. China, *., 178*. (A. B. R. 185; 

 R B, 412.) 



P. sanguinolenta (bloody-juicedX JL greenish-yellow; 

 many-flowered, shorter than the leaves. July. L orate-lanceo- 

 late, quite glabrous. Sierra Leone, 1822. Plant trailing, full of 

 blood-coloured juice. (B. M. 2532.) 



Greek for around; e.g., as in Perianth. 



The outer, or accessory, organs in 

 the flower, i.e., the sepals and petals, which protect the 

 essential organs of reproduction, or the true flower, in 



Fie. 84. PETALOID PERIANTH, as 



in LOium caneotar 



botanical language, .., the stamens and pistiL In most 

 flowers, the perianth is doMe, consisting of an outer 

 circle of green sepals, and an inner circle of coloured 



FIG. 85. SINGLE PERIAXTH, as seen in A 



*** 



petals (as in Abutilon, Fig. 83). In the LUiaeeas, and 

 other plants, the perianth, though double, consists of parts 

 very much alike, and all petaloid (LOiwn omcoior, Fig. 



Perianth. continued. 



84) ; while in others .$., Juiunw, Ac. aU the parts are 

 sepaloid. Often one of the circles is wanting, and the 

 missing circle is usually the petals, though (as in 

 Anemone, Fig. 85) those present may appear petaloid. 

 Often such single perianths are sepaloid (Mercurial**). 

 In a good many plants (Willows, Arum,), there is no 

 trace of perianth. In many plants, the bracts are modi- 

 fied to simulate part of a perianth (sepaloid bracts of 

 Dianthus, and petaloid bracts of Corn** suecica). 



Included under Hyacinthus (which 

 tee). 



PERICAUJS. Included under Senecio (which 

 tee). 



PEBJCALYMN A. Included under Lepto*perm*m. 

 FEBJCABP. The rind or shell of all fruits. 



PEBJCIiADIUM. The sheathing base of a leaf 

 when it expands and surrounds the supporting branch; 

 the dilated, sheathing base of some petioles. 



FERICIANIUM. The involucre of the flower-heads 

 in Composite. 



FEBJCYCUL A synonym of Licuala (which tee). 

 pyiRTniS^fc'^r, y yrn.TpT^Tf.wrTg xhe outer cellular 

 layer of bark, below the epidermis. 



from peri, around, and derma, 

 skin). A group of Fungi, including only a few forms, 

 parasitic on Com/ercp. Those of most importance are 

 P. elatinum (also called JEfidium elatinum), which 

 gives rise to swellings on the branches of the Silver 

 Fir (Abies pectinata), and P. Pirn, with its variety 

 P. oricolitm, on the Scotch Fir (Pintu eyltestrig) and 

 the Austrian Fir (P. aiutriaca), in pleasure grounds, as 

 well as in forests. The genus belongs to the group of 

 "red rusts," and the Fungi in it form a mycelium in 

 the tissues of the leaves and branches of the host-plants. 

 On the surface of the diseased parts there appear, after a 

 time, cylindrical, laterally flattened, or conical outgrowths, 

 called peridia, Ain. to $in. high, and Ain. to in. broad ; 

 the larger forms being on the branches, and the smaller 

 on the needles. These outgrowths are formed of a thin 

 layer of cells, which tears irregularly at the tip, and 

 sets free numerous small, round, orange-coloured spores, 

 to reproduce the plant. 



P. (JifidtHm) elatinum is not very frequent ; but where 

 it is present the tree sometimes bears a large number 

 of swellings on the branches, often near the base of one 

 or more small branches, or supports what are known as 

 " witch-besoms " on the larger branches. Both kinds of 

 growth are the work of the Fungus; and the difference 

 is due chiefly to age. The swellings vary from the size 

 of a Hazel nut to that of a closed fist; the bark is the 

 part most enlarged. The mycelium grows in the bark 

 and the pith-rays and pith, and often causes separation 

 of the bark from the wood, and the death of the wood 

 in patches. In most cases, it does not kill the branch 

 entirely ; but the mycelium is perennial, and the growth 

 on the branch continues to increase year after year. 

 When branches grow from the surface, they often branch 

 very freely, but remain stunted ; and this is repeated 

 year by year, the "witch-besoms" being thus formed. 

 The leaves on the diseased shoots are short and stunted, 

 and are usually covered with peridia. Though not 

 usually, or only very slowly, dangerous to the life of 

 the tree, the growths are very objectionable, as they 

 greatly spoil its appearance. The only effectual remedy 

 is cutting off the diseased branches as soon as the 

 swellings appear, in order to prevent the disease from 

 spreading to other trees. 



P. Pint grows in branches of Firs, and almost always 



