axillary or in dense clusters,
blooming in summer.

1a. Flower-clusters axillary --2.

1b. Flower-clusters in terminal spikes or panicles, sometimes also
axillary --3.

2a. Plant prostrate or decumbent; seed about 1.5 mm. broad
=Pigweed, Amaranthus blitoides.=

2b. Plant erect or ascending, widely branched; seeds about 1 mm.
broad (3-10 dm. high) =Tumble Weed, Amaranthus graecizans.=

3a. Principal leaves with a pair of spines at their base
=Thorny Amaranth, Amaranthus spinosus.=

3b. Spines none at the base of the leaves --4.

4a. Weedy plants of cultivated or waste ground; flowers monoecious
or polygamous; pistillate flowers with a calyx (Pigweed) --5.

4b. Plants of swamps or stream-banks; flowers dioecious; pistillate
flowers without calyx (Water Hemp) --7.

5a. Spikes short, 1-8 cm. long, crowded in dense ovoid panicles; the
terminal spike not conspicuously elongated beyond the appressed or
ascending lower ones =Pigweed, Amaranthus retroflexus.=

5b. Spikes slender, 1-12 cm. long; the terminal spike greatly exceeding
the short inconspicuous divergent lower ones --6.

6a. Bracts subulate, sharply awned =Pigweed, Amaranthus hybridus.=

6b. Bracts merely acuminate =Pigweed, Amaranthus paniculatus.=

7a. Flowers in leafy spikes, or the lower in separate clusters
=Water Hemp, Acnida tuberculata.=

7b. Flowers in separate distinct clusters
=Water Hemp, Acnida tuberculata var. subnuda.=

PHYTOLACCACEAE, the Pokeweed Family

Herbs with alternate entire leaves, small flowers without petals, and a
many-celled ovary.

One species in Michigan, 1-2 m. high, with numerous racemes of whitish
flowers, in late summer, followed by dark-purple berries
=Pokeweed, Phytolacca decandra.=

NYCTAGINACEAE, the Four-o'Clock Family

Herbs, with opposite entire leaves and flowers in small clusters
surrounded by a broad open calyx-like involucre; the true calyx colored
like a corolla; petals none (4-8 dm. high; flowers purple, in summer).

1a. Leaves lanceolate or narrower, sessile
=Umbrella-wort, Oxybaphus hirsutus.=

1b. Leaves ovate, petioled
=Umbrella-wort, Oxyba