Senna armata (S. Watson) Irwin & Barneby

Spiny senna, desert senna

Similar species

	You are here Senna armata	Encelia farinosa
Common Name	spiny senna	brittlebush
Plant	Shrubs up to 3′ (1 m) in height. They are densely branched, any many of the branches terminate in sharp spines.	Forms rounded bushes 12–59″ (30–150 cm) high.
Leaves	Leaves are on long and narrow branchlets, in 2-4 opposite pairs. Each leaflet is ⅛–3/16″ (4–6 mm) around, and ovate. Leaf pairs aren’t quite symmetric. Leaves are dropped entirely most of the time.	Leaves are triangular (ovate to deltoid), blue-gray, and 1–3″ (3–8 cm) long. Fine matted plant hairs on the leaves give them a silvery appearance.
Flowers	Yellow, or salmon pink, occurring singly or in clusters in leaf axils. Each flower has five petals, and is ⅝–⅞″ (1.6–2.4 cm) in diameter. Flower petals are not evenly distributed, so the flower has bilateral symmetry but not radial symmetry. Flowers appear from March to July.	Yellow flower stalks extend outward from the domelike bush. Each flower is 1–1¼″ (3–3.5 cm) around. Each is a composite flower, comprised of a central disc with many yellow or purple-brown disc florets, and yellow or orange-yellow ray florets.
Fruit	Pods are ⅞–1½″ (2.5–4 cm) long, straight, and con­tain a few seeds.	1/16–3/16″ (3–6 mm), with no visible pappus.
Range/ Zones
Habitats	In sandy or gravelly washes, at elevations of 328–4593′ (100–1400 m).	Dry, gravelly slopes and open sandy washes, at elevations up to 3281′ (1 km).

Senna armata description by Thomas H. Kent, not updated.

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