pter] 



€fyz Ercaffttrg nf 3Sotang. 



enclose one flower. There are two known 

 species, both natives of California— P. dry- 

 marioides and P. macroptera. The first is 

 a smooth trailing much-branched annual 

 herb, with opposite stalked leaves having 

 rounded or bilobed blades, and small in- 

 volucres single in the axils of the leaves, 

 their margins crested with slender teeth. 

 In P. macroptera the involucral leaves en- 

 large as the fruit ripens, so that when 

 mature they are half an inch across. In 

 both the involucral leaves are formed like 

 the valves of an oyster-shell. [A. A. B.] 



PTEROSTYRAX. The name applied to 

 a Japanese shrub, constituting a genus of 

 Styracacece. The shrub is covered with 

 stellate hairs, has sharply serrated ovate 

 leaves, and bears axillary and terminal 

 panicles of flowers. The tube of the calyx 

 is adherent for a short distance to the 

 ovary; the stamens are ten, five longer 

 than the rest, all partially united below 

 into a tube ; the ovary contains numerous 

 ovules, arranged in two rows ; the style 

 being awl-shaped, jointed above the base, 

 and the stigma somewhat five-lobed. Fruit 

 dry, somewhat woody, partially adherent 

 to the tube of the calyx, the limb of which 

 is expanded, and forms, as it were, Ave 

 wings to the fruit, whence the name of the 

 genus. [M. T. M.] 



PTEROZONIUM. A genus of ferns be- 

 longing to the Gymnogrammece, and sepa- 

 rated indeed from Gymnogramma itself, 

 where some botanists still retain it. The 

 only species, P. reniforme, a South Ameri- 

 can species, of dwarf stature, with simple 

 reniform coriaceous fronds, has the sori 



Pterozonium reniforme. 



placed in so remarkable a position, that 

 it has been made the type of a distinct 

 genus. The sori are linear, and radiato- 

 furcate, but laterally approximate, so that 

 they soon become confluent into a broad 

 horseshoe-shaped band on the back of the 

 reniform frond. This confluence of the 

 contiguous lines of spore-cases indicates 

 a considerable approach towards the struc- 

 ture of Piatyloma. [T. MJ 



PTERYGIUM. Any wing or membranous 

 expansion of seeds. 



PTERYGODIUM. A genus of Cape or- 

 chids, small terrestrial leafy plants, with 

 sheathing-based leaves, and solitary or 

 racemose pale-yellow or greenish flowers, 

 which have their upper sepal agglutinated 

 to the petals and forming a hood, whence 

 one species is called Monk's Cowl. The 

 two lateral sepals are free and spreading ; 

 and the lip adnateto the face of the column, 

 and furnished with a large tongue-formed 

 appendage at its base. [A. S.J 



PTERYGOTA. A name under which it 

 is proposed to separate Sterculia alata from 

 the rest of the genus on account of its 

 winged seeds. It is an East Indian tree, 

 of which the seeds are said to be narcotic. 



PTILOTA. A beautiful genus of rose- 

 spored Algce belonging to the natural order 

 Ceramiacew, and distinguished by their 

 compressed inarticulate frond, which is re- 

 peatedly pinnate. P. plumosa is confined 

 to our northern coast, growing constantly 

 on Lamina via digitata. P. sericea is more 

 finely divided, and is common on our 

 coasts, growing on rocks, and occasionally 

 on Fucus serratus. It is one of the plants 

 often used for making up seaweed pic- 

 tures. A species which occurs at the 

 Cape is one of the most beautiful of Algce, 

 and there are other southern species. The 

 genus does not apparently occur on the 

 shores of the United States. [M. J. P..] 



PTILOTUS. A genus of Amarantliacem, 

 consisting of glabrous annuals from Aus- 

 tralia and the Moluccas, with narrow al- 

 ternate leaves, and terminal heads of 

 flowers with shining scarious bracts ; peri- 

 gone of five sepals, with three bracts at 

 the base ; stamens five, united at the base, 

 without intermediate staminodes ; anthers 

 two-celled ; utricle indehiscent one-seeded, 

 enclosed in the woolly sepals. [J. T. S.] 



PTISAN. A medicated drink prepared 

 from the flowers of Malva sylvestris. 



PTYCHODE. An internal membrane 

 overlying the external skin of a cell inter- 

 nally ; the protoplasm. 



PTYCHOMERIA. A genus of Burman- 

 niacece consisting of six or seven small 

 slender leafless annuals from tropical Bra- 

 zil and Guiana. They are allied to Dictyo- 

 stegia, but remarkable for the long slender 

 tube of the perianth, its three outer lobes 

 being more or less three-cleft, whilst the 

 three inner ones are very small or entirely 

 deficient. 



PTYCHOTIS. A small genus of annual 

 or biennial plants belonging to the Umbel- 

 Hferce, found in the south of Europe, on the 

 borders of the Mediterranean, in Egypt, 

 Arabia, and India. It is distinguished by 

 the compound umbels of white flowers 

 being surrounded by a few-leaved Invo- 

 lucre, by the margin of the calyx being 

 five-toothed, and the petals notched or slit 

 at the apex, with a long inflexed point 

 proceeding from the sinus and cohering 

 with the middle vein; and by the two 

 halves of the rough laterally compressed 



