“The Illustrated Flora of Illinois Flowering Plants: Pokeweeds, Four o’clocks, Carpetweeds, Cacti, Purslanes, Goosefoots, Pigweeds, and Pinks” (Southern Illinois University Press, 2001), by Robert H. Mohlenbrock, provides details of each flower family and its habitat in Illinois. Learn more about the surroundings of each plant and flower. If you are from the Illinois area, you may find that some of these plants will do great in your growing area.
Annual, biennial, or perennial (in Illinois) herbs, shrubs, vines, or trees; leaves usually opposite, simple, without stipules; ﬂowers perfect (in Illinois) or unisexual, variously arranged, subtended by bracts or an involucre of bracts; sepals united, forming a campanulate or funnelform calyx persistent in fruit, often petaloid, 3- to 5-toothed or -lobed; petals absent; stamens 1–5; ovary inferior (in Illinois) or supe- rior, 1-locular; style 1; fruit a 1-seeded utricle enclosed by the calyx tube.
There are about thirty genera and three hundred species in this family. Most of them are in the American tropics. Several genera have ornamental value, including Myrabilis, the four-o’clock, and Bougainvillea, a tropical woody vine or shrub.
There is often an involucre of bracts that is calyxlike in appearance and that sub- tends or encloses one or more ﬂowers. Those plants that have the greatly enlarged involucre are sometimes segregated into the genus Oxybaphus. The fruit, which in- cludes the 1-seeded utricle enclosed by the calyx tube, is referred to as the anthocarp.
All of our species except M. jalapa were originally described in the genus Allionia, but that genus has winged anthocarps.
1. Anthocarp (fruit) smooth or 5-angled; involucre not papery or membranaceous, scarcely or not enlarged in fruit…1. M. jalapa
1. Anthocarp (fruit) prominently 5-ribbed; involucre paper or membranaceous, greatly en- larged in fruit.
2. Leaves petiolate, ovate, rounded or cordate at the base…2. M. nyctaginea
2. Leaves sessile or nearly so, linear to lanceolate to oblong, not rounded or cordate at the base.
3. Leaves linear to linear-lanceolate, 1–5 mm wide…3. M. linearis
3. Leaves lanceolate to oblong, some or all of them more than 5 mm wide.
4. Stems densely hirsute, at least at the base and at the nodes…4. M. hirsute
4. Stems glabrous or puberulent in lines…5. M. albida
Perennial herb from woody or ﬂeshy roots; stems erect, to 1 m tall, much branched, glabrous to sparsely pubescent; leaves opposite, ovate to deltate, acuminate at the tip, cordate or rounded at the base, to 15 cm long, to 8 cm broad, entire, glabrous to sparsely pubescent, occasionally viscid, with petioles up to half as long as the
blades, or the uppermost leaves nearly sessile; ﬂowers in glomerules at the ends of the branches, the glomerules on peduncles 1– 2 mm long; bracts united, campanu- late, up to 15 mm long, the lobes linear-lanceolate to lance-ovate, ciliolate, bristle- tipped, about twice as long as the tube, the involucre of bracts subtending 1 ﬂower; calyx trumpet-shaped, 4 – 6 cm long, the limb 2.0 –3.5 cm across, variously colored, notched around the edges, glabrous to sparsely pubescent on the outer surface; sta- mens 5, as long as or slightly longer than the calyx; staminodia 3 or 6; anthocarp oval to ovoid, 8 –10 mm long, 5-angled, rugose or verrucose, glabrous or puberu- lent, dark brown to black.
Common Name: Garden Four-o’clock.
Habitat: Disturbed soil, sometimes on refuse heaps.
Range: Adventive in much of the United States; apparently native to tropical America.
Illinois Distribution: The only collection of this plant is from Grundy County.
This is the only species of Mirabilis in Illinois that does not have a greatly enlarged, membranaceous involucre of bracts. The anthocarp is 5-angled but not conspicuously 5-ribbed.
Mirabilis jalapa, the garden four-o’clock, is sometimes planted as a garden ornamental but not as often today as in the past.
This species ﬂowers from June to October.
Allionia nyctaginea Michx. Fl. Bor. 1 : 100. 1803.
Oxybaphus nyctagineus (Michx.) Sweet, Hort. Brit. 429. 1830.
Oxybaphus ﬂoribundus Choisy in DC. Prodr. 13 (2) : 433. 1849.
Perennial herb from a thickened taproot; stems erect, to 1 m tall, branched, glabrous to sparsely pubescent; leaves opposite, lance-ovate to ovate, acute to acuminate
at the apex, rounded to cordate at the base, to 12 cm long, to 7 cm broad, entire, glabrous, on petioles up to half as long as the blades, or the uppermost leaves nearly sessile; ﬂowers perfect, 3 –5 together subtended by an involucre of bracts; involucre up to 6 mm long in ﬂower, up to 15 mm long in fruit, 5-lobed, the lobes obtuse to subacute, pilose, becoming enlarged, veiny, and often pinkish purple in fruit; calyx
5-lobed, pink or purple; stamens 3 –5, exserted; anthocarp hardened at maturity, narrowly obovoid, 4 – 6 mm long, densely pilose, rugose or verrucose, prominently 5-ribbed, grayish brown; seed obovoid, 2.5 –3.0 mm long, light brown.
Common Name: Wild Four-o’clock; Umbrella-wort.
Habitat: Disturbed soil; particularly common along railroads.
Range: Manitoba to Montana, south to Colorado, Texas, and Louisiana; adventive in much the rest of the United States, including Illinois. Illinois Distribution: Common throughout the state.
The wild four-o’clock is a common plant along railroad rights-of-way.
When in fruit, the involucre of bracts often becomes rather hand- somely pinkish purple. This species differs from the other species in Illi- nois that have an enlarged, membranaceous involucre in its petiolate, cordate leaves.
Mirabilis nyctaginea ﬂowers from May to September.
Allionia linearis Pursh, Fl. Am. Sept. 728. 1814.
Oxybaphus linearis (Pursh) B.L. Robins. Rhodora 10 : 31. 1908.
Perennial herb from an elongated taproot; stems decumbent to ascending to erect, to 1 m tall, glabrous or puberulent in the lower half, short-hairy to viscid in the up- per half, glaucous; leaves opposite, linear to linear-lanceolate, acute at the tip, cuneate at the base, to 10 cm long, up to 5 mm broad, entire, glabrous or viscid- pubescent, often glaucous on the lower surface, sessile or nearly so; ﬂowers perfect,
3 together subtended by an involucre of bracts; involucre up to 4 mm long in ﬂower, up to 2 cm long in fruit, 5-lobed, glandular-pubescent; calyx deeply 5-lobed, the lobes retuse, pink to bright purple, to 10 mm long, sparsely pilose; stamens 3 – 5, usually slightly exserted; anthocarp obovoid, 4 –5 mm long, pubescent, rugose, 5-ribbed, olive-brown; seed obovoid, 2.5 –3.0 mm long, light yellow-brown.
Common Name: Linear-leaved Wild Four-o’clock.
Habitat: Disturbed sandy soil and in railroad ballast.
Range: North Dakota to Montana, south to Arizona and Texas; Mexico;
sparingly adventive in the eastern United States.
Illinois Distribution: Known from Cook, Madison, St. Clair, and Will counties.
The only collection of this plant made during the twentieth century was by Julian Neill in 1947 in St. Clair County.
This species is readily distinguished by its linear leaves.
Mirabilis linearis ﬂowers from June to August.
Reprinted with Permission from The Illustrated Flora of Illinois Flowering Plants: Pokeweeds, Four o’clocks, Carpetweeds, Cacti, Purslanes, Goosefoots, Pigweeds, and Pinks” by Robert H. Mohlenbrock and Published by Southern Illinois University Press.
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