FLOWERING PLANTS AND FERNS OF ARIZONA 279 



1. AMARANTHUS. amaranth 



Plants herbaceous, annual; leaves alternate, petioled. the blades 

 pinnate-veined; flowers mostly unisexual, small, commonly subtended 

 by a bract and 2 bractlets; perianth segments 2 to 5, separate; 

 stamens 2 to 5; utricle 2- or 3-beaked by the persistent styles. 



These plants are commonly known as pigweed. Their seeds, pro- 

 duced in great abundance, are an important food supply for birds 

 such as the common dove, whitewing, and quail. Indians of several 

 tribes gathered the young leaves for greens and the seeds for meal. 

 In southern Arizona carelessweed (A. palmeri), abundant in river 

 bottoms, is sometimes cut for hay, and is relished by stock, in both the 

 green and dry state. Most of the species are weeds of cultivated land 

 and roadsides, flowering in summer. 



Key to the species 



1. Sepals of the pistillate flowers broadly spatulate, with a flabelliform or obovate 

 blade considerably wider than the claw, at apex obtuse, truncate, or emargi- 

 nate, often apiculate, exceptionally acutish (2). 

 2. Utricle not circumscissile, narrow, nearly equaling the calyx; plants mono- 

 ecious, the staminate flowers often very few; leaf blades lanceolate or 



narrowly oblong, not more than 3 cm. long 1. A. obcordatus. 



2. Utricle circumscissile, subglobose, considerably shorter than the calyx (3). 

 3. Plants dioecious; petioles slender, equaling or longer than the broad, 

 rhombic-ovate blades; flowers mostly in elongate, naked, compound 

 spikes, these single or forming terminal panicles; bracts risidly 



spinose-tipped; sepals often denticulate 2. A. palmeri. 



3. Plants monoecious, the staminate flowers sometimes very few; inflores- 

 cences leafy, at least below (4). 

 4. Axillary flower clusters much shorter than the petioles; leaf blades 

 linear-lanceolate to ovate-lanceolate; bracts shorter than the 

 flowers; sepals of the pistillate flowers usually with fimbriate 



margins 3. A. fimbriatus. 



4. Axillary flower clusters mostly equaling or longer than the petioles; 

 leaf blades linear to elliptic; bracts equaling or longer than the 

 flowers; sepals of the pistillate flowers with entire or denticulate 



margins 4. A. prixglei. 



1. Sepals of the pi-tillate flowers linear, lanceolate, oblong, elliptic, or occasionally 

 narrowly spatulate, with the blade little wider than the claw; plants mo- 

 noecious, the staminate flowers sometimes very few (5). 

 5. Utricle not circumscissile; leaf blades ovate, up to 8 cm. long; flowers in a 



rather small panicle of slender spikes: sepals 3 5. A. gracilis. 



5. Utricle circumscissile (6). 



6. Flowers all in small, glomerate or racemiform, leafy-bracted, axillary 

 cluster^ 7 . 

 7. Sepals 4 or 5: seeds 1.5 mm. in diameter: stems commonly prostrate: 



plant glabrous or nearly so 6. A. blitoides. 



7. Sepals 3 or fewer: seeds 1 mm. or less in diameter: stem.- commonly erect 

 or ascending (8). 

 8. Plant densely vi>cid-pubescent; leaf blades crispate. 



7. A. PUBES( JENS. 



8. Plant glabrous or puberulent, not viscid: leaf blades flat or nearly so. 



8. A. GRAECIZAXS. 



6. Flowers mostly in terminal and axillary, compound spikes, these often 



clustered in a terminal, leafy or nearly naked panicle: leaf blades mostly 



rhombic-ovate; species of similar appearance, difficult to distinguish 



(9). 



9. Sepals of the pistillate flowers, or some of them, acute or acuminate at 



apex (10). 



10. Seeds usually whitish and dull: terminal spike more or less drooping; 



sepals equaling or shorter than the fruit 9. A. caudatus. 



