PTERIDIUM 



PTERIS 



1463 



sporangia borne on a marginal line-like receptacle as in 

 Pteris (Fig. 2011) and covered with a marginal indu- 

 sium, but with an additional membranous indusium 

 within the receptacle. Commonly known as Pteris. 



aquilinum, Kuhn. Lvs. scat- 

 tered from an underground rhi- 

 zome, 2-9 ft. high, ternately com- 

 pound. Field and waste places in 

 some of its forms throughout the 

 world. L. M. UNDERWOOD. 



2011. Fruiting pinnule 

 of common brake. 



Pteridium aquilinum. 

 Natural size. 



PTfiRIS (Greek name for a 

 fern, from a word meaning wing; 

 alluding to the prevalence of pin- 

 nate forms). Polypodidcece. A 

 large genus of widely distributed ferns with the spor- 

 angia borne on a marginal line-like receptacle that con- 

 nects the free ends of the veins, and with the more or 

 less altered margin of the leaf rolled over to form a con- 

 tinuous indusium. Many of the forms are among the 

 commonest species of ferns in the trade and are quite 

 generally used for table decoration. For culture, see 

 Fern. 



INDEX. 



8. L. refers to supplementary list. 



A. Veins free throughout. 



B. Lvs. simply pinnate, the lower 



pinnce not divided 1. 



BB. Lvs. simply pinnate, but the 



lower pinnae forked 2. 



3. 

 4. 



BBB. Lvs. ivith lowest pinnce pinnate. 5. 



6. 



BBBB. Lvs. with lowest pinnce Mpin- 

 n at if id. 



c. Lowest pinnce enlarged 7. 



8. 

 9. 



cc. Lowest pinnce not enlarged ..10. 

 AA. Veins free, except for a single low 



arch next the midvein 11. 



12. 

 AAA. Veins uniting, forming copious 



meshes .. ..13. 



longifolia 



Cretica 



serrulata 



ensiformis 



inaequalis 

 semipinnata 



quadriaurita 

 heterophylla 

 tremula 

 scaberula 



biaurita 

 Wallichiana 



leptophylla 



1. longifolia, Linn. Lvs. 1-2 ft. long, 4-9 in. wide, 

 lanceolate, often narrowed below; pinnae 20-30 on each 

 side, linear, entire. Tropical regions all around the 

 world, extending to southern Florida. Var. Mariesii, 

 Hort. Fronds shorter and pinnules straighter, the plant 

 keeping closer to the pot; a good horticultural form. 



2. Cretica, Linn. Lvs. 6-12 in. long, on slender, straw- 

 colored stalks, consisting of a terminal pinna and 2-6 

 opposite sessile pairs, the upper often decurrent, the 

 lower pairs cleft nearly to the base into 2 or 3 pinnules. 

 Quite generally distributed in tropical regions, extend- 

 ing to central Florida. Many varieties are in cult., of 

 which var. albo-lineata, Hort. (Fig. 2012), is one of the 

 finest, with broader pinnae and a broad, central, whitish 

 band. Var. major and var. n6bilis are larger horticul- 

 tural forms, and var. magnifica and var. Mayii (P. 

 Mayii) are still more developed. 



3. serrulata, Linn. f. Lvs. 3-12 in. long, on slender 

 brownish stalks, consisting of a terminal pinna and 5-6 

 pairs of lateral ones, the upper ones decurrent and the 

 lower forked into 2 or 3 branches or with second branch 

 above the basal one ; pinnae narrow, the indusium not ex- 



tending to the apices, which are sharply serrulate. China 

 and Japan. Many monstrous and distorted forms appear 

 in cult., giving rise to such varietal names as angustata, 

 cristata, cristata nana compacta, cristata variegata, 

 densa, Gilbertii, Ouvrardi (P. Ouvrardi, Hort.), voluta, 

 etc., but these cannot be regarded as true varieties in 

 any scientific se^ase. 



4. ensifbrmis, Burm. Lvs. of 2 sorts, the sterile with 

 elliptic or elliptic-lanceolate segments, the lower pinnae 

 5-7-parted, the upper gradually simpler; sporophylls 

 similar but taller and with longer and much narrower 

 divisions. India to Polynesia; often confused with the 

 preceding species, as both are more or less common in 

 cult. Var. Victdriae (P. Victoria, Hort.) is a garden va- 

 riety with leaves variegated with white. 



5. inaequalis, Baker. Lvs. ovate - deltoid, 18-24 in. 

 long, 10-15 in. wide, with 4-5 pairs of pinnate or pinnati- 

 fid pinnae followed by 2-3 pairs of broadly linear simple 

 ones and ending in a long, terminal, irregularly pin- 

 natifid portion; divisions of the lower sides of the pin- 

 nae uniformly much longer and larger than the upper 

 ones. China and Japan. 



2010. Ptelea trifoliata. the Hop Tree, in fruit (X 



6. semipinnata. Linn. Lvs. 12-18 in. long, the upper 

 portion simply pinnate with decurrent pinnae, the 4 or 

 more lowest pinnatifid on the lower side, the upper side 

 of the secondary rachises bordered by a narrow lamina. 

 India, China, Japan and the East Indies. Var. Bausei, 

 (P. Bausei, Hort.) is a garden form. 



7. quadriaurita, Retz. Lvs. up to 2-3 ft. long, on 

 strong, pale stalks, with a terminal central pinna cut 

 down to the rachis into numerous linear-oblong lobes, 

 and below this several similar pinnae on each side, the 

 lowest of which are usually again compound with simi- 

 lar but smaller ones branching from the lower side at 

 base. All tropical regions. Var. argyraea (P. argyrcea, 

 Moore) is a form with a white band down the centers 

 of the pinnae. Var. tricolor (P. tricolor, Linden) is simi- 

 lar but has a tinge of red in addition. 



8. heterophylla, Linn. Lvs. 6-8 in. long, on pale stalks, 

 of 2 sorts ; sterile Ivs. elliptic,deeply incised ; sporophylls 

 narrowly linear-elliptic, with broad indusia and sterile 

 apices ending in 2-3 teeth; both sorts bipinnate in the 

 lower portions. West Indies to Brazil. Sometimes 

 referred to a distinct genus, Anopteris. Var. internata 

 (P. internata, Moore) is a garden variety with smaller 

 sporophylls and broader segments. 



