Grand Canyon Century Plant

Agave phillipsiana is known from only four sites within Grand Canyon National Park. All are found on terraces along permanent waterways. Three of the sites are near pre-Columbian agricultural features or habitation sites. Two sites occur near a Kayenta-Anasazi Pueblo cliff dwelling (A.D. 1000–1150), on a terrace presumably once farmed by the early inhabitants. Agave phillipsiana possesses traits that would be advantageous to those harvesting it for food, since it is a plant that freely offsets and has open rosettes with large, long leaves that are easily cut. The species is possibly an ancient cultivar selected by pre-Columbian people from populations related to A. palmeri, A. colorata Gentry, or other closely related taxa.

Plants acaulescent, freely suckering; rosettes solitary to cespitose, 7.5–10 × 7.5–10 dm, open. Leaves erect, 76–78 × 10–11 cm; blade glaucous-green to dark green, lightly cross-zoned, lanceolate, rigid, adaxially concave toward apex, abaxially convex at base; margins straight or undulate, armed, teeth single, well defined, brittle, 4–7 mm, 1–2.5 cm apart, interstitial teeth (2–)3–7, mostly along distal 2/3 of margins; apex not conspicuously incurved, spine brownish gray, slender, 2.5–4 cm. Scape 2.7–5.5 m. Inflorescences narrowly paniculate, not bulbiferous, open; bracts persistent, triangular, 1–2+ cm; lateral branches 9–16, ascending to nearly perpendicular, comprising distal 1/3–1/2 of inflorescence, longer than 10 cm. Flowers 32–45 per cluster, erect, 7.4–8.6 cm; perianth greenish cream, tube campanulate, 15.5–20 × 15–23 mm, limb lobes persistent and often leathery during and after anthesis, spreading, unequal, 15–22 mm, apex often flushed with maroon; stamens long-exserted; filaments inserted subequally below rim of perianth tube, erect, yellow, 4.8–6.4 cm, apex flushed with maroon; anthers yellow, 17–25 mm; ovary 3.3–4.6 cm, neck slightly constricted, 4–8 mm. Capsules not seen. Seeds unknown. 2n = ca. 120.

Ariz.

Flowering early summer.

Sandy to gravelly places with desert scrub; 700--1100m.

Agave phillipsiana is a rare species of flowering plant in the asparagus family known by the common names Grand Canyon century plant and Phillips agave. It is endemic to Arizona in the United States, where it lives only in Grand Canyon National Park. It is a perennial herb or shrub.

This plant forms one or more rosettes of large lance-shaped green to gray-green leaves with teeth along the edges and spines at the tips. The leaf blades grow up to 78 centimeters long by 11 wide. The flowering stalk grows up to 5.5 meters tall. The branching inflorescence has clusters of many flowers each 7 or 8 centimeters wide or more which are greenish and cream-colored with hints of maroon. Long stamens protrude from the flower corollas.

There are four occurrences of this plant, all within Grand Canyon National Park, where they grow on terraces next to rivers. Some occurrences are in locations inhabited by indigenous peoples long ago, who may have farmed the plant and selected it for its ease of propagation and harvest.

The plant's numbers are low but it grows in rugged terrain in a national park, which may protect it somewhat from human threats. It grows in sandy, gravelly, rocky soils in desert scrub, slopes, and hillsides.