Ideas for a slope

Silphium

Silphium
A genus of perennials that are part of the larger Daisy family. These make stunning plants for a focal point or the back of the landscape border.They are long lived, lasting decades but are slow to establish developing a huge taproot before much growth above ground.
They thrive in full sun and are very clay and drought tolerant. They are propagated from seed though division is possible with care while dormant.

Silphium asteriscus
A perennial, reaching up to 6 feet.
Hardy zones 5 to 9 in full sun to partial shade. Very drought tolerant.

Silphium integrifolium
Reaches up to 8 ( rarely over 6 ) x 3 feet, that is native to central and eastern U.S.
The long pointed leaves are stemless.
It bears large yellow flowers, up to 3 inches across, are borne on terminal clusters over a long season from mid summer to early autumn.
Hardy zones 4 to 8 in full sun to partial shade on well drained soil including clay.

* photos taken on Aug 4 2013 in Bayfield, Ontario


Silphium laciniatum ( Compass Plant )
A perennial, reaching a maximum size of 14 x 4 ( rarely over 10 ) feet, that is native to prairies of central North America ( from North Dakota to Michigan & northern Ohio; south Texas to Alabama ).
Slow growing, plants take 5 years to mature.
The deeply-cut, pinnately-lobed leaves, up to 36 ( rarely over 18 ) inches in length, are oriented north and south. The deep green leaves clasp the hairy white stems.
The bright yellow daisy-like flowers, up to 5 inches across, are borne in clusters during mid summer to early autumn.
Up to 100 flowers may be borne on a plant at a time.
Hardy zones 3 to 8 in full sun on deep, slightly alkaline or neutral soil. The very deep taproot up to 13 feet deep on mature plants enable it to tolerate severe drought.

Silphium perfoliatum ( Cup Plant )
An upright, large clumping perennial, reaching a maximum size of 12 x 4 ( rarely over 5 ) feet, that is native to prairies and moist open woods in central North America ( from South Dakota to southern Ontario to southern New England; south to Oklahoma to Mississippi to Georgia ). Can be used as a specimen plant or as a perennial hedge. With time the Cup Plant may form a large clump. A spectacular large perennial, it has massive untapped potential as a low maintenance landscape plant.
The oppositely arranged, coarse, irregularly toothed, ovate leaves, up to 14 inches in length, are deep blue-green. The leaves clasp the stems forming a cup where they unite.
The showy, yellow, daisy-like flowers, up to 4 inches across, are borne during mid summer to mid autumn.
The stems are 4-angled.
Hardy zones 3 to 8 in full sun.

* photos taken on Aug 25 2011 @ Scott Arboretum, Swarthmore, PA




* photo taken on Aug 20 2011 @ Brookside Gardens, Wheaton, MD


* photo taken by Douglas Ladd @ USDA-NRCS PLANTS Database. Midwest wetland flora


Silphium terebinthinaceum ( Prairie Dock )
A perennial, reaching a maximum height of 10 x 6 ( rarely over 8 ) feet, that is native to central North America ( from Minnesota to southern Ontario to Ohio; south to Missouri to Louisiana to Georgia ).
The upright leaves are up to 3 feet in length.
The profuse, golden-yellow, daisy-like flowers, up to 2 inches across, are borne during late summer.
Hardy zones 3 to 8 in full sun on well drained soil. Very drought tolerant due to its deep taproot.

* USDA-NRCS PLANTS Database