AN ENCYCLOPEDIA OF HORTICULTURE. 



127 



Filocerens continued. 



F. Brunnowii (Brunnow's). /. unknown. Stem erect, cylin- 

 drical, many ribbed, bright green, thickly beset with shining 

 spots ; ribs nine to twelve, vertical, rounded, uneven when 

 young, later on pretty smooth. Prickles about thirteen, cen- 

 tral one much the longest, surrounded in the younger parts of 

 the plant by long white hairs. Bolivia, 1870. See Fig. 151 (for 

 which, as well as for Fig. 152, we are indebted to Herr Fr. Ad. 

 Haage, jun., of Erfurt). 



P. Curtisii (Curtis'), fl., tube olive-green, 2in. long, |in. thick, 

 expanding with many imbricating segments ; within this is a 

 series of pale rose-coloured, ovate petals ; style deep rose-colour ; 

 stigma of seven or eight rays. Spring and summer. Plant 3ft. or 

 more high, l$in. to 2in. in diameter, erect, straight or somewhat 

 flexuous, eight to ten-angled, beset with little tufts of wool ; from 

 these arise a spreading cluster of aculei, and from a tuft of this 

 description springs the flower. Grenada. SYN. Cerent Royeni. 

 (B. MTaffl.) 



P. Dautwitzil (Dautwitz's).* Stem oblong or fusiform, bright 

 green ; traversed from base to apex by twenty-one shallow ribs, 

 bearing closely-set tufts of small, white, spreading straight 

 spines, and covered throughout, but more especially at the top, 

 with a dense coating of long, white, cottony hair. Northern 

 Peru, 1870. See Fig. 152. 



P. fossulatns (grooved). Stem erect, club-shaped, with ten 

 to twelve obtuse angles ; sutures undulated, with a depression 

 above each areole ; spines pale brown, the central one very 



Filocerens continued. 



grey hairs of an old man's head When young, the stems 



are fleshy and succulent, but, as they get old; their tissue 

 becomes tilled with an extraordinary quantity of small, sand-like 

 grains, composed of oxalate of lime, not less than from 60 to 80 

 per cent, having been found in individual stems " (" Treasury of 

 Botany "). Mexico and Guatemala. 



PILOPHORA. A synonym of Manicaria (which 

 see). 



PILOSE. Covered with long, soft hairs ; having the 

 form of hairs. 



FILOSELLA. Included under Hieracium. 



FILOSIUSCULUS. Slightly hairy. 



FILULARIA (from pilula, a little ball or pill; 

 alluding to the shape of the heads containing the repro- 

 ductive organs). Pillwort. ORD. Marsileacece. A small 

 genus (three species) of obscure little aquatic plants, in- 

 habiting temperate Europe, Western Asia, Australia, and 

 North America. Rootstock creeping under water. Leaves 

 solitary, erect, setaceous. " Capsule globose, two to four- 

 celled, two to four-valved at the top ; cells each with a 

 longitudinal, parietal placenta, on which are inserted 



FIG. 153. UPPER PORTION OF PLANT OP PILOCEREUS HOULLETII, with Bud and Fruit (natural size). 



strong, lin. long, the outer ones ten to twelve, depressed; 

 hairs white, very strong, with a tuft on the apex. h. probably 

 20ft. A noble and very distinct, but scarce species. Peru (?). 

 (G. C. 1873, 197.) 



P. Honlletll (Houllet's).* fl. a kind of violet, with a suspicion of 

 rose and yellow ; segments very small, numerous, lanceolate, re- 

 curved ; tube short, smooth, with a few pointed, reddish-green 

 scales. Stem strong, grey-green ; ribs seven or eight ; prickles 

 nine, straw-coloured, central one longest. The younger parts of 

 the plant are covered with a white felt. See Fig. 153. (R. H. 

 1862, 427.) 



P. senilis (aged).* Old Man Cactus. "A cylindrical-stemmed 

 plant, 1ft. or more in height ; but in Mexico, its native country, 

 it attains a height of 20ft. to 25ft., with a diameter of 9in. or 

 lOin., and its fluted character gives it somewhat the appearance 

 of an architectural column. The stem is divided into thirty or 

 forty narrow furrows, with corresponding ridges, which are fur- 

 nished, at very short distances, with tufts of white spines, sur- 

 rounded by numerous long, flexible, white hairs, resembling the 



many pyriform, membranous sacs; sacs in the upper 

 part of the cell full of microspores immersed in mucilage ; 

 those in the lower part contain each one macrospore. 

 Microspores globular, full of antherozoids. Macrospores 

 ovoid, with an outer coat of prismatic cells, pierced 

 by a funnel-shaped opening, through which an inner, 

 glassy coat finally protrudes. In germination, a pro- 

 thallus is developed at the top of the protruded portion 

 of the inner coat of the macrospore, which bursts and 

 frees it. After expulsion, an archegonium is formed on 

 the prothallns, and fertilisation takes place by the 

 contents of the microspore" (Hooker). P. globulifera 

 is found in damp meadows, among grass, especially where 

 they have been overflowed with water during winter; 

 it is widely distributed over England and Scotland, but 



