Plants to 30 m, 37 dm diam.; strongly heterophyllous, (often 2 or more trunks near base). Bark pale tan, deeply furrowed. Branchlets tannish brown, becoming paler tan to bone- white by third year, round, 1-3(-5) mm diam., slender to coarse, glabrous, glabrate, or sparsely to densely hairy, (yellowish). Winter buds yellow-brown, usually densely stiffly hairy, resinous (resin yellow); terminal buds (4-)7-11(-14) mm; flowering buds separated on branchlets, (5-)11-18(-22) mm. Leaves: petiole distally flattened at right angle to plane of blade, 1-6(-9) cm, 3/5-3/4 blade length; blade rhombic-ovate to broadly triangular-ovate, (1.5-)4-8 (-14) × (1.5-)3-8(-11) cm, w/l = 3/5-1/1, base cuneate to truncate or cordate, basilaminar glands 0, margins translucent, ciliate, apex short- to long-acuminate, surfaces yellowish green, resin stains not evident, glabrous or densely hairy; preformed blade margins coarsely crenate-serrate midblade, teeth 3-10(-15) on each side (graded, rounded), sinuses (0.2-)0.5-4(-5.5) mm deep; neoformed blade margins finely crenate-serrate much of margin, teeth (10-)20-30(-45) on each side, sinuses 0.1-1 mm deep. Catkins loosely (10-)15-25(-35)-flowered, (3-)4.5-10(-14 in fruit) cm; floral bract apex deeply cut, not ciliate. Pedicels 1-4 (-5.5 in fruit) mm. Flowers: discs broadly cup-shaped, not obviously oblique, entire, (2.5-)4-7(-9) mm diam.; stamens (30-)40-60(-70); anthers truncate; ovary 2-4-carpelled, spherical; stigmas 2-4, flat, platelike, expanded. Capsules spherical, (5-)6-11 mm, glabrous, 2-4-valved. Seeds 9-15(-25) per placenta. 2n = 38.

Plant: Dioecious tree; to 30 m tall, usually not clonal; bark pale tan and deeply furrowed on the trunk. TWIGS tannish white, turning bone white to tan by the third year, glabrous or densely short-pilose; winter buds yellow-brown, resinous, usually hirsute Leaves: leaves broadly triangular-ovate, 4-14 cm long; margins coarsely crenate-serrate with 3-10 graded teeth on each side (up to 25 on leaves of long shoots), the largest, near the base of the blade, usually with sinuses more than 2 mm deep INFLORESCENCE: CATKINS 4-13 cm long; bracts glabrous; pedicels 3-4 mm long Flowers: with broadly cup-shaped disk, this 5-9 mm wide in fruit; stamens 30-70 Fruit: CAPSULES 6-10 mm long, globose, usually 4-valved Misc: Floodplains, canyons, springs and other moist places; 8-2200 m (25-7300 ft); Feb-Apr (fr. Mar-May) Notes: winter buds resinous; seeds with long, white hairs References: J.C. Hickman, ed. The Jepson Manual. Kearney & Peebles. Arizona Flora. ASU specimens. Eckenwalder, James E. 1992. Salicaceae. Ariz.-Nev. Acad. Sci. 26(1)2.

Eckenwalder 1992, Heil et al. 2013, Allred and Ivey 2012

Common Name: Fremont cottonwood Duration: Perennial Nativity: Native Lifeform: Tree General: Trees up to 30 m tall with open crown; bark whitish, smooth, deeply furrowed at maturity; year-old twigs mostly pubescent. Leaves: Alternate, clustered near tips of branchlets, on flattened petioles that are nearly as long as the leaf blades; blades deltoid, 4-7 mm long and about as wide or wider, slightly cordate or cuneate at base and sharply pointed at the tip, with margins coarsely and irregularly toothed, and surfaces bright green and glabrous. Flowers: Catkins 4-13 cm long, with male and female catkins on the same tree; each flower subtended by a deeply cup-shaped disc, 3-9 mm wide. Fruits: Capsules globose or ellipsoid, 6-10 mm long; splitting open into 4 segments (valves) to release many tiny seeds attached to abundant white cottony hairs. Ecology: Found along streams banks and near lakes and ponds, below 6,500 ft (1981 m); flowers March-June. Distribution: CA, NV, UT, CO, AZ, NM, CO, TX; south to c MEX. Notes: A common, often large tree of southwestern streamsides, identified by its coarsely-toothed, shiny triangular leaves, large size, and spreading crown. This is the only broad-leaf cottonwood found in the low deserts of Arizona, but farther north and east the taxonomy is not so simple. Some authorities treat Fremont cottonwood as a variety of P. deltoides (see Allred and Ivey 2012, which recognizes 4 intergrading, hybridizing varieties of P. deltoides in New Mexico). Distinguish P. fremontii from other similar broad-leaf cottonwoods based on its leaf margins which are finely crenate-serrate with 20-30 teeth on each side of the blade (coarsely serrate with fewer than 20 teeth in other varieties); it lacks a pair of glands at the junction of leaf blade and petiole (P. deltiodes var. wislizeni also lacks these glands but vars. deltoides and occidentalis have the glands); and its short fruiting pedicels, 2-5 mm long, and large floral discs, 4-9 mm wide in fruit (P. deltoides var. wislizenii has fruiting pedicels 7-15 mm long and narrower floral discs, 1-4 mm wide in fruit). Ethnobotany: Hopi use this tree to make Katchina dolls. Used by the Navajo to make many game pieces. Etymology: Populus is the classical Latin name for poplar trees; fremontii honors US Army officer and western explorer John C. Fremont (1813-1890) who collected this species in California. Synonyms: Populus deltoides var. fremontii Editor: SBuckley 2010, FSCoburn 2015, AHazelton 2017