34 NORTH AMERICAN FLORA [VotumME 16 
Fronds several meters long ; rhizome short-creeping, thickly clothed with short black- 
ish few~celled flaccid hairs; stipe and rachis stramineous throughout, subterete, stoutish, 
up to 3 mm. in diameter; primary branches evident as mere protuberances upon the rachis 
or up to 5mm. long, the terminal bud not invariably abortive; secondary (geminate) pinnae 
up to 50 cm. long, petiolate (3-6.5 cm.), rotund-ovate to pentagonal in outline, pinnate or 
at the base bipinnate, the rachis strongly flexuous, stramineous, narrowly marginate above; 
tertiary segments 2-4 pairs, nearly equal in length, the lowermost petiolate (1-4 cm.), 
cordate at the base, sometimes triangular and piunate, bearing a pair of shorter alternate 
quaternary segments at the base, or subpalmately cleft into 3 or 4 elongate quaternary seg- 
ments similar to the middle tertiary segments, these simple or dichotomously cleft, the 
divisions equal or unequal; upper tertiary segments mostly simple, falcate, the uppermost 
often joined to the terminal segment, this sometimes greatly elongate (up to 30 cm.) and 
either single or binate; middle tertiary segments (or their main divisions) in general linear- 
oblong, 10-20 cm. long, 1.5-3 cm. broad, or the fertile ones linear-lanceolate and narrower ; 
costae stout, not nodose-articulate at the base, subflexuous, elevated; veins alternate, 
oblique, elevated, anastomosing, forming 4 or 5 ranks of areoles upon each side of the 
costa, the costal row unequally obdeltoid, the outer ones irregularly hexagonal, directed 
toward the margin; leaf-tissue rigidly herbaceous, lustrous upon both surfaces, slightly 
paler below, the veins and costae nearly glabrous, the margins obscurely crenulate-repand ; 
sporangiophores up to 6 mm. long, close, sessile, serrate; spores verrucose. 
TYPE LOCALITY: Oaxaca, Mexico. 
DISTRIBUTION: Southern Mexico to Costa Rica; also in Venezuela. 
ILLUSTRATION : Kunze, Farrnkr. pl. 173. 
6. Lygodium venustum Sw. Jour. Bot. Schrad. 1801’: 503. 1803. 
Primary rachis subterete, usually yellowish-stramineous, very narrowly marginate, up 
to 2.5 mm. in diameter, pubescent; primary branches up to 1 cm. long, densely pubescent, 
the terminal bud usually dormant; sterile secondary (geminate) pinnae petiolate (1.5-3 
cm.), oblong or broadly oblong, 15-25 cm. long, 8-20 cm. broad, once-pinnate, acute or 
acuminate, the rachis nearly straight, densely pubescent, slightly alate toward the apex; 
tertiary segments 5-8 pairs, approximate or mostly apart, slightly smaller toward the apex, 
all but the uppermost stalked, deltoid-ovate from a cordate base, 4-10 cm. long, 1.5-4 cm. 
broad at the base, the costa nodose-articulate at the base and emitting a dichotomous branch 
“upon either side, the segment thus subpalmately 5-lobed, the middle lobe greatly elongate, 
usually at least twice as long as the lateral, lanceolate to oblong-lanceolate, 1-1.8 cm. broad, 
acute or obtuse, the margin deeply crenate-serrate or sometimes pinnately lobed, the lobes 
or crenations close, denticulate-serrate; costae elevated, stout, nearly straight, excurrent 
to the apex, pilose or pubescent; veins commonly opposite, or subopposite, very oblique, 
elevated, subpinnately branched, the branches close, pilose or pubescent, the hairs of the 
lower surface usually much shorter; leaf-tissue herbaceous, usually subopaque, glabrous or 
short-pubescent. Fertile secondary (geminate) pinnae similar to the sterile or often bipin- 
nate, the lower tertiary segments with shorter basal lobes or 1-3 pairs of short mostly 
opposite quaternary segments, the lowest of these inequilateral and often subpalmately 
lobed; sporangiophores solitary upon the mostly shallow lobes, serrate, up to 8 mm. long; 
spores minutely verrucose. 
TYPE LOCALITY: Brazil. 
DISTRIBUTION: Mexico and Central America, southward to Brazil and Peru; West Indies (not 
common). 
ILLUSTRATION : Breyn, Exot. Pl. Cent. A1. 96. 
7. Lygodium mexicanum Presl, Rel. Haenk. 1: 72. 1825. 
Lygodium Schiedeanum Presl, Abh. Bohm. Ges. Wiss. V. 4: 370. 1845. 
Lygodium commutatum Presl, Abh. Bohm. Ges. Wiss. V. 4: 370. 1845. 
Rachis subterete, stramineous to yellowish-brown, very narrowly marginate, up to 
2.5 mm. in diameter; primary branches 5-10 mm. long, sparingly pubescent ; sterile sec- 
ondary (geminate) pinnae petiolate (0.5-3 cm.), broadly ovate to deltoid-ovate, 15-28 cm. 
