Opuntiads of the USA

HOME

Opuntia macrorhiza

Copyright Dave Ferguson and Joe J. Shaw, 2006

Introduction

Opuntia macrorhiza is a small Opuntia, seldom reaching 12 inches in height or more than 2-3 feet across. O. macrorhiza has a large geographic range, being found from New Mexico and Utah east into Ohio, Kentucky, Tennessee, Alabama, and Louisiana. Reports (D. Ferguson) suggest the species may be found in Wyoming, South Dakota, Minnesota.

The cladodes may have spines or may lack spines. Different populations of the species show different spine trends; areoles may have 0-5 spines each. Nearly spineless forms may have a few spines at along pad tips. Glochids are numerous, typically prominent. The flowers are yellow with red at the base of the inner tepals; flower color may be pale-yellow or dark yellow. All yellow flowers, or red-orange flowers, have been reported.

Technical Description

Succulent subshrub: evergreen clumping plants with few, low branches, or trailing upon soil rooting occasionally from cladodes, typically with enlarged roots (tuberous roots). Cladodes adhere firmly to each other and the plant does not "shatter," pads dehydrate and become wrinkled in winter or drought.

Spines: present or absent on pads, distal, typically acicular and terete, white, sometimes pale yellow or cream-yellow, darkening to red-brown or rust-brown at base, 1-5(6) cm.

Flowers: tepals yellow (rarely to orange, pink, red, or magenta), inner tepals commonly orange to red at base creating an orange to red center for flower, stigmatic lobes pale yellow or cream (sometimes greenish in far western plants), anthers yellow

Fruits: 20 (to 50) mm long, 12-20 mm wide, elongate with stipitate base, reddish or green-red when mature, fleshy with juicy pulp. Fruit color is highly varied, more commonly light in east than in west, varying from deep purplish-red through red, orangey or pinkish, to greenish. Fruit interiors vary similarly, but dark fruits may be light inside and visa-versa.

Seeds: tan, disc-shaped (sometimes irregular) in outline, 4-5 mm diameter, sometimes irregular and thick or with buckling, with visible rim to 0.5 mm.

Note: Dave Ferguson reports, "…the seeds of O. macrorhiza are fairly uniform in shape, relatively thick, and generally smaller than those of O. cymochila. However, they are somewhat similar to those of many other smallish, juicy-fruited species. They do vary from plant to plant and from place to place, but not too much. They may appear red, magenta, grey or brown, because of dried pulp on the seed…"

Opuntia macrorhiza, Travis County, TX (photo by Ed Utley)	Opuntia macrorhiza, Travis County, TX (photo by Ed Utley)	Opuntia macrorhiza, Travis County, TX (photo by Ed Utley)
Opuntia macrorhiza, Travis County, TX (photo by Ed Utley)	Opuntia macrorhiza, Travis County, TX (photo by Ed Utley)	Opuntia macrorhiza, Travis County, TX (photo by Ed Utley)
Opuntia macrorhiza, Travis County, TX (photo by Ed Utley)	Opuntia macrorhiza, Travis County, TX (photo by Ed Utley)	Opuntia humifusa, can be confused with O. macrorhiza
Cultivated Opuntia macrorhiza, plant on left (smaller pads) is from Houston, TX, plant on right (larger pads) is from LaGrange, TX.	Same two plants as image at left--positions reversed, flower on left is Opuntia macrorhiza va. grandiflora (red coloration at base of inner tepals barely visible)	Opuntia macrorhiza, shrivelled pad, February 2008, Dripping Springs, TX
Opuntia macrorhiza var. grandiflora, LaGrange, TX, April 2007	Close-up of plant at immediate left	Opuntia macrorhiza var. grandiflora, LaGrange, TX
Opuntia macrorhiza, garden plant	Opuntia macrorhiza, garden plant (O. pusilla in pot at bottom left)	Opuntia macrorhiza, garden plant
Opuntia macrorhiza, garden plant	Opuntia macrorhiza, garden plant	Opuntia macrorhiza with twisted-stunted flowers (garden plant)
Unusual pink-flowered O. macrorhiza, photo from Craig Howe, 2008	Opuntia macrorhiza, garden plant	Close-up of plant at immediate left
Opuntia macrorhiza, garden plant	Cultivated O. macrorhiza from Grapeland, TX	Close-up of semi-dehydrated Opuntia macrorhiza cladode
Close-up of Opuntia humifusa, can be confused with O.	Opuntia macrorhiza, garden plant, from general area of Inks Lake State Park, Burnet, TX	Same plant as immediate left, different view, plants often have spinate pads as well as pads mostly lacking spines
Opuntia macrorhiza, dehydrated for winter, near LaGrange, TX	Opuntia macrorhiza var. grandiflora, near LaGrange, TX--showing tuberous roots	Opuntia macrorhiza, near LaGrange, TX
Opuntia macrorhiza, near Espanola, NM	Same plant as left, roadside debris (white paper napkin) provides size information	Opuntia macrorhiza, Ojo Caliente, NM
Opuntia macrorhiza, Rio Grande River bottom, Albuquerque, NM	different view of stem at immediate left, plant dehydrated in winter	Cultivated Opuntia macrorhiza in full bud (back), with O. valida (foreground)
Opuntia macrorhiza growing between pine trees, Bastrop, TX, Apil 2008	Opuntia macrorhiza (in center of photo), Pace Bend Park, near Austin, TX, April 2008	Opuntia macrorhiza, Pace Bend Park, northeast of Austin, TX, with O. pyrocarpa, O. sanguinicola, and Echinocereus reichenbachii, April 2008