graptopetalum

Southern Arizona Stonecrops & Rock Mat
Arizona Rare Cactus Photos

Stonecrops
Graptopetalum bartramii & Graptopetalum rusbyi

Graptopetalum ("writing petal") is in the Stonecrop Family (Crassulaceae). With its rosette of thick, succulent leaves,
it is similar to close relatives Sedum, Echeveria and Dudleya, but the flower petals are yellow with red spots and stripes.
The two U.S. species are found almost entirely in southern Arizona and are protected as Salvage Restricted by state law.
G. bartramii is restricted to southern AZ and G. rusbyi is found in southern and central AZ. G. bartramii is a BLM and USFS Sensitive Species. Both plants are rare and have similar habitat requirements. They grow in upland desert, chaparral, and Madrean evergreen woodland. G. bartramii tolerates higher elevations than G. rusbyi. The plants grow on north-facing slopes in moist, organic-rich pockets of soil on the downhill side of a rock or a sheltering plant. They are often found with Selaginella (spikemoss) and/or well-developed cryptobiotic soil crust. If the plants lose their protective shelter or soil, they dry out and die.
THREATS: Trampling by humans or cattle. Off-road driving. Collection.

Graptopetalum bartramii

G. bartramii growing at 4200 feet on a granite outcrop with Lechugilla (Agave schottii).


FLOWER BUDS: In a panicle (open clusters on branches scattered along the stalk). Photo taken in late August.	LEAVES: Broadest near the tip.


FLOWERS bloom in fall or early winter. Photos above were taken October 16, 2007. Open flowers are about 1 cm across.


SEEDPODS persist until the next flowering season.

Graptopetalum rusbyi


LEAVES: Broadest at the center. Mature rosettes have fewer leaves than G. bartramii.


FLOWERS bloom in spring. In a cyme (open cluster at the top of the stalk) or less commonly in a short raceme (single stalked flowers scattered along the stalk).

Cockerell's Stonecrop
Sedum cockerellii

In southern Arizona's "sky island" mountains, this stonecrop grows in tight clusters on damp, shady rocks.
Photos below were taken on the same outcrop as one of the Graptopetalum bartramii photos above,
and both species were growing in thin soil among Selaginella spikemoss.

Leaves are tiny but thick and succulent. This cluster is the same
diameter as a single large Graptopetalum rosette.

Rock Mat
Petrophytum caespitosum

This unusual plant resembles a succulent but is actually a miniature shrub in the Rose Family (Rosaceae).
It grows on bare dry limestone or marble throughout much of the mountain West, ranging as far north as Montana.
It is uncommon in southern Arizona, where it is found only on high outcrops in a few mountain ranges.
The southern portion of its range (AZ, NM, TX, and Mexico) is not well defined.
THREATS: Collection, trampling.


Anchored in deep cracks, plants form small mounds on bare limestone.	Dead plants look like tiny gnarled trees.


Tiny white flowers bloom in late summer. Seedstalks shown above..	The evergreen leaves are light bluish green.	Leaf rosettes have tiny silky white hairs.