Opuntia cespitosa Raf.

Eastern Prickly Pear

© SRTurner

Family - Cactaceae

Habit - Succulent, sprawling shrub with somewhat woody rootstock.

Stems - Highly modified into thick, flat pads (cladodes), often in chains of 2-6, often produced with the flat side parallel to the ground, obovate, rotund, or elliptical in outline, strongly glaucous-green when developing, aging dark green or light gray-green, cross-wrinkling during the winter months, 4-19 cm x 3-11 cm, 4-19 mm thick, with 4-6 (generally 5) areoles per diagonal row. Leaves glaucous, ascending parallel to the pad surface or slightly spreading, 5.5-6.8 mm long.

	Pads (cladodes).
© SRTurner

Spines - Spines smooth to the touch, 1-2 per areole (most commonly 1), 1.5-4.3 cm long, 0.78-0.87 mm in diameter, these dark at the base during development but maturing bony-white, and finally dark gray in age, typically spreading in one plane from the areoles (i.e., in line with one another) with primarily 1 spine, or occasionally 2 of roughly the same length or 1 long and 1 short and slightly deflexed, rarely 3 spines produced from the areoles; in age the mid-cladode and especially the basal cladode spines tend to deflex. Glochids 2-3 mm long, dark red or amber, aging light to dark brown.

© SRTurner

Flowers - Outer tepals triangular to ovate, inner tepals 9-10, 3-6 cm long, basally tinged reddish, orange, or reddish-pink, obovate with a mucronate tip, filaments yellow, reddish basally, stigmas white to cream with 6-10 lobes.

	Flower buds.
© SRTurner

	Flower.
© SRTurner

	Flowers on pads.
© SRTurner

	Tepals.
© SRTurner

	Stamens and stigma lobes.
© SRTurner

Fruits - Berries 2-5 cm long, the surface with glochids but no spines, the areoles sometimes restricted to the apical rim, remaining fleshy with age, green, sometimes becoming reddish-or purplish-tinged with age. Seeds 3.5-4.5 mm long, the raised rim relatively short (extending about 0.5 mm beyond the seed body) and smooth.

	Fruits.
© SRTurner

Flowering - May - July.

Habitat - Glades, prairies, bluffs, stream terraces, pastures, railroads, open disturbed areas.

Origin - Native to U.S.

Lookalikes - Other species of Opuntia

Other info. - This cactus is by far the most widespread species of Opuntia in Missouri, common throughout most of the state. It occurs throughout most of the eastern half of the continental U.S., though uncommon to rare in northern regions. Prickly pear cactus is easily identified to genus by its appearance, though differentiation of species can be difficult.

Until recently, Missouri's dominant cactus was thought to be O. humifusa, but more recent work suggests that O. cespitosa is the correct taxon. Unraveling species differences within this complex requires close attention to specialized plant structures which are obscure to many botanists. Studies are further hampered by the difficulty in vouchering specimens and the unpleasantness of working with them. Due to their succulence, specimens placed into a plant press in the normal fashion will tend to mildew unless specific actions are taken to prevent this. The large spines, while inconvenient, are not the plant's most unpleasant aspect. That distinction belongs to the glochids, which are much smaller but extremely sharp, barbed needles notorious for becoming painfully embedded in the skin. These can be difficult to remove due to the barbs, but if allowed to remain can result in ulceration and a dermatitis which can persist for months. The optimal method for removal appears to be two-staged: first, to extract as many as possible using forceps and a dissecting microscope; second, to cover the area with household white glue and a strip of gauze, allow to dry, and then quickly and forcibly rip the strip away.

Despite this unpleasantness, the flowers are undeniably beautiful and can be produced in profusion. The plants are hardy and easy to propagate vegetatively from pads. Whether the species is appropriate for a garden setting is left to the reader's judgment.

Photographs taken at Greensfelder Park, near Pacific, St. Louis County, MO, 5-23-2009, along the Al Foster Trail near Glencoe, St. Louis County, MO, 4-17-2010, at Sand Prairie Conservation Area, Scott County, MO, 9-24-2011, St. Joe State Park, St. Francois County, MO, 6-10-2013, and on Ellis Island, near West Alton, St. Charles County, MO, 7-3-2017 (SRTurner).