1785. Phil. Bot. 45. 1789.

[Franseria Cav. Icon. 2: 78. pl. 200. 1793.]

Hispid or tomentose branching herbs, with the aspect of Ambrosias, sometimes woody at the base, with mostly alternate lobed or divided leaves, and small monoecious greenish heads of discoidal flowers, the staminate in terminal spikes or racemes, the pistillate solitary or clustered in the upper axils. Involucre of the pistillate heads ovoid or globose, closed, 1-4-celled, 1-4-beaked, armed with several rows of spines and forming a bur in fruit; corolla none or rudimentary; style deeply bifid, its branches exserted; stamens none; achenes obovoid, thick, solitary in the cells; pappus none. Staminate heads sessile, or short-peduncled, their involucres broadly hemispheric, open, 5-12-lobed; receptacle chaffy; corolla regular, the tube short, the limb 5-lobed; style undivided; anthers scarcely coherent; mucronate-tipped. [In honor of Joseph Gaertner, 1732-1791, German botanist.]

About 25 species, natives of America. In addition to the following, some 12 others occur in the western and southwestern United States. Type species: Xanthium fruticosum L. f.

Plant hirsute: annual: soines of the fruiting involucre long, flat.

1. G. acanthicarpa.

Leaves densely white-tomentose beneath; spines short, conic; perennials. Leaves bipinnatifid.

2. G. discolor.

Leaves pinnately divided, the terminal segment large.

3. G. tomentosa.

1. Gaertneria Acanthicarpa (Hook.) Britton. Hooker's Gaertneria

Fig. 4129

Ambrosia acanthicarpa Hook. Fl. Bor. Am. 1: 309.

1833. Franseria Hookeriana Nutt. Trans. Am. Phil. Soc.

(II.) 7: 345. 1841. Gaertneria acanthicarpa Britton, Mem. Torr. Club 5: 332. 1894. Franseria acanthicarpa Coville, Contr. Nat. Herb.

4: 129. 1893.

Annual, erect or diffuse, paniculately branched, 1°-2° high; stem hirsute or hispid. Lower and basal leaves slender-petioled, bipinnatifid, 2'-4' long, the upper short-petioled or sessile, once-pinnatifid, or merely lobed; racemes of sterile heads usually numerous, 1'-3' long; fruiting involucres clustered in the axils, 3"-4" long, commonly 1-flowered, armed with numerous long flat straight spines.

In moist soil, Saskatchewan to western Nebraska and Texas, west to British Columbia and California. Sand-bur. Recorded from Minnesota. July-Sept.

Gaertneria tenuifolia (A. Gray) Kuntze, a southwestern perennial species with pinnately dissected leaves, the fruiting involucre only about 1" long, is recorded as extending eastward into Kansas.

1 Gaertneria Acanthicarpa Hook Britton Hooker s Ga 800

2. Gaertneria Discolor (Nutt.) Kuntze. White-Leaved Gaertneria

Fig. 4130

Ambrosia tomentosa Nutt. Gen. 2: 186. 1818. Not Gaertneria tomentosa (A. Gray) Kuntze.

Franseria discolor Nutt. Trans. Am. Phil. Soc. (II.) 7: 345. 1841.

Gaertneria discolor Kuntze, Rev. Gen. Pl. 339. 1891.

Erect or ascending from perennial rootstocks, branched, about 1° high. Leaves nearly all bipin-natifid, petioled, densely white-tomentose beneath, green and pubescent or glabrate above, 2'-5' long; sterile racemes narrow, commonly solitary, 1'-2' long; fruiting involucres clustered in the axils, finely canescent, about 3" long, mostly 2-flowered, armed with short sharp conic spines.

In dry soil, South Dakota, Nebraska, Wyoming, Kansas, Colorado and New Mexico. Aug.-Sept.

2 Gaertneria Discolor Nutt Kuntze White Leaved Gae 8012 Gaertneria Discolor Nutt Kuntze White Leaved Gae 802

3. Gaertneria Tomentosa (A. Gray) Kuntze. Woolly Gaertneria

Fig. 4131

Franseria tomentosa A. Gray, Mem. Am. Acad. 4: 80. 1849.

G. tomentosa Kuntze, Rev. Gen. Pl. 339. 1891.

Gaertneria Grayi A. Nelson, Bot. Gaz. 34: 35. 1902.

Erect from a deep perennial root, usually branched at the base, 1°-3° high. Leaves pin-nately lobed or divided, finely and densely to-mentose on both sides, or ashy above, the terminal segment lanceolate or oblong-lanceolate, acuminate, serrulate or entire, very much larger than the 2-6 rather distinct.narrow lateral ones; sterile racemes solitary, 2'-4' long; fruiting involucres solitary, or 2-3 together in the upper axils, ovoid, finely canescent or glabrate, 2-flowered, about 3" long, armed with subulate-conic, very acute, sometimes curved or hooked spines.

On rich prairies and along rivers, western Nebraska, Kansas and Colorado. Aug.-Sept.