ParT 1, 1922] AMBROSIACEAE 
23 
many spines in several series and ending in one or more 2-lipped or 2-toothed beaks, the lips 
or teeth more or less incurved and the outer one much longer. 
Type species Franseria ambrostoides Cav. 
Beak solitary; fruit l-celled, usually 1-flowered. 
Plant herbaceous, at most shrubby at the base only; beak very 
oblique, one lobe much longer; fruit not densely hairy. 
Fruit 7-10 mm. long; spines not hooked, either decidedly flat- 
tened or channeled. 
Plant annual, erect; inflorescence a leafy panicle; leaves not 
canescent. MI. 
Plant perennial, decumbent at the base, with a rootstock; 
inflorescence simple, racemose; leaves canescent at least be- 
neath. 
MONTANAE. 
. MARITIMAE. 
Fruit 2-4 mm. long; spines more or less hooked at the apex. Ill. TENUIFOLIAE. 
Plant shrubby; beak not very oblique, the lobes not very unequal 
in length; fruit densely hairy. IV. ERIOCENTRAE. 
Beaks 2-8; fruit of as many flowers and cells. 
Fruit rather small; spines usually less than 30 (only in F. Magdalenae 
40-60), in 2—6 series, either flattened or channeled above, or 
else very short and conic, rarely strongly hooked. 
Leaves pinnatifid. 
Paleae of the staminate receptacle equaling or exceeding 
the flowers, 3-nerved, boat-shaped; leaves simply pinnate 
with broad toothed divisions or some simple. V. TOMENTOSAE. 
Paleae of the staminate receptacle shorter than the flowers, 
l-nerved, usually very narrow; leaves deeply dissected. 
Spines of the fruit few, short, conic or conic-subulate, not 
flattened, only slightly if at all hooked; leaves inter- 
ruptedly pinnatifid. VI. DiscoLorEs. 
Spines elongate, many, 20—60; leaves pinnatifid but usu- 
ally without smaller lobes between the larger ones; 
shrubby plants with white bark. VII. ALBICAULES. 
Leaves not pinnatifid, simple, merely lobed or toothed. 
Spines of the fruit subterete, merely channeled, hooked. 
Leaves cordate in outline, deeply 3-—5-lobed, triple- 
ribbed. VIII. CorpDIFOLIAg. 
Leaves ovate or lanceolate in outline, pinnately veined 
and cleft. IX. ARBORESCENTES. 
Spines more or less flattened, not hooked, those of the lower 
series broad and connate at base; leaves ovate, lanceo- 
late, or deltoid in outline, merely toothed or indistinctly 
lobed. ; X. CHENOPODIFOLIAE. 
Fruit large, usually more than 1 cm. long; spines more than 100, 
subulate, strongly hooked, in many series. 
Leaves not spinescent; paleae of the staminate receptacle hya- 
line, 1-nerved. XI. AMBROSIOIDES. 
Leaves and the involucral lobes spinescent; paleae of the stami- 
nate receptacle herbaceous, several-nerved, longer than the 
flowers. XII. ILIcrFo.rak. 
I. MONTANAE 
Leaves divided practically to the midrib; lobes linear or oblong. 1. F. acanthicarpa. 
Leaves not divided to the midrib; lobes obovate. 
Spines 15-30 in about 4 series 2. F. montana. 
Spines 10-18 in 2 or 3 series. 3. F. Palmeri. 
II. MARITIMAE 
Spines of the fruit thick, subulate, only somewhat flattened or channeled on 
the upper side; leaves bipinnatifid. 
Stem and inflorescence strigose with short hairs. 4. F. bipinnatifida. 
Stem and inflorescence more or less villous with long white hairs. 5. F. villosa. 
Spines of the fruit decidedly flattened. 
Leaves pinnatifid or bipinnatifid. 6. F. Lessingit. 
Leaves merely crenate or lobed. 7. F. Chamissonis. 
III. TENUIFOLIAE 
Leaves tomentulose as well as strigose beneath. 8. F. linearis. 
Leaves not tomentulose beneath. 
Leaves bi-or tripinnatifid; fruit hirsutulous as well as glandular; plant if at 
all suffruticose only at the base. 
Siem strigose with short appressed or incurved hairs. 
Leaves finely and densely white or grayish-strigulose. 
Paleae of the staminate receptacle with broad rhombic 
or spatulate tips; leaves white-canescent. 9. F. canescens. 
Paleae of the staminate receptacle filiform or narrowly linear, 
only slightly clavate at the tip; leaves grayish. 10. F. strigulosa. 
Leaves coarsely strigose, rarely canescent. 
