Click the number at the start of a key lead to highlight both that lead and its corresponding lead. Click again to show only the two highlighted leads. Click a third time to return to the full key with the selected leads still highlighted.
| 1 Plants forming low, spreading shrubs. |
| ..2 Tepals yellow with red or maroon bases adaxially. |
| ....3 Erect-spreading shrubs, chains of cladodes radiating from center of plant, the flat surface generally held perpendicular to the ground surface; cladodes remaining turgid throughout the year; stigma usually green; fruit barrel-shaped (widest near the middle); [of c. TN] |
| ....3 Spreading shrubs, plants clump forming or with chains of cladodes spreading from the central axis of the plant, the flat surface generally parallel to the ground surface; cladodes becoming cross-wrinkled during fall and winter months, fruit clavate (widest towards the tip); [collectively widespread in our area]. |
| ......4 Central spines mostly 0-2 (when 2, both spines generally in the same plane, i.e., both reflexed or both erect); spines monomorphic (central spines only produced); [widespread in eastern US, mostly west of the Appalachian Mts. and east of the MS River] |
| ......4 Central spines mostly 0-3 per areole (when 2-3, the lower spines generally reflexed and the upper spine porrect on upper cladodes); spines monomorphic (central spines only) or dimorphic (with smaller hairlike radial spines and larger central spines); [mostly west of the Mississippi River, in our area as a rare disjunct in w. MS] |
| ..2 Tepals entirely yellow or greenish yellow. |
| ........5 Cladodes spineless; cladodes never easily disarticulating; areoles typically 4-5 per diagonal row at the widest point of the cladode; [central Appalachian Mts. and n. Atlantic Coast, disjunct in nc. MS] |
| ........5 Cladodes generally with 1 or more spines per areole on at least some of the uppermost areoles; cladodes easily disarticulating or not; areoles typically 1-4 per diagonal row at the widest point of the cladode; [widespread in Atlantic and Gulf Coastal Plain and Atlantic Piedmont]. |
| ..........6 Terminal cladodes easily disarticulating, 0.8-11.1 cm × 0.6-3.4 cm, often cylindrical or only moderately flattened; spines strongly retrorsely barbed; terminal cladodes with 1-2 areoles per diagonal row at the widest point of the cladode |
| ..........6 Terminal cladodes disarticulating or not, 3.1-17.7 cm × 2-9 cm, strongly flattened; spines retrorsely barbed (to the touch) or not; cladodes with 3-4 areoles per diagonal row at the widest point of the cladode. |
| ............ 7 Seeds with funicular envelope smooth, only moderate, if any, protrusion of the cotyledons and hypocotyl, cladodes typically scalloped-margined, elliptical or rotund in outline, spines delicate, 0.7-0.9 mm in diameter; [restricted to the outer Gulf Coastal and Atlantic Coastal Plain] |
............ 7 Seeds with funicular envelope bumpy, cotyledons and hypocotyl noticeably protruding, cladodes typically smooth-margined, obovate or rotund in outline, spines stout, 0.95-1.3 mm in diameter; [of Atlantic Southern Piedmont, FL panhandle along the coast west to coastal MS and e. LA, otherwise mostly inner Gulf Coastal and Atlantic Coastal Plain] |
| 1 Plants forming erect or ascending shrubs or small trees. |
| ............ ..8 Tepals red, pink, yellow with red midribs abaxially, or yellow with red or reddish maroon bases adaxially; stamens either thigmonastic (i.e., moving towards the stigma in response to manipulation of filaments) or not. |
| ............ ....9 Cladodes generally spineless; tepals red or pink, erect; stamens and style exserted past the corolla; filaments red or pink, the stamens not thigmonastic; [alien, rarely persistent or naturalizing in FL] |
| ............ ....9 Cladodes generally spiny; tepals yellow and variously tinged red or maroon adaxially or abaxially; stamens and style included within the corolla; filaments yellow or yellow green, the stamens thigmonastic. |
| ............ ......10 Erect shrubs or small trees; spines chalky-white; cladodes dark, glossy green; tepals yellow with red abaxial midrib; stigmas white to cream; fruit clavate (widest towards the tip), often proliferous; [alien, known from FL only in our area] |
| ............ ......10 Spreading or erect shrubs; spines pale white or white with maroon or brown bands; cladodes light, glaucous green, dull; tepals yellow basally tinged red or maroon adaxially; stigmas usually greenish; fruit barrel-shaped (widest near the midpoint), not proliferous; [of nc. TN] |
| ............ ..8 Tepals yellow or greenish yellow; stamens thigmonastic. |
| ............ ........11 Spines white (at least on second year’s growth), generally round at the base and thus round in cross section, strongly retrorsely barbed or not; glochids stramineous-colored; mature fruit red, greenish yellow or pink; [restricted to FL] |
| ............ ........11 Spines white or yellow (on second year’s growth), often flattened at the base and thus lacunar or elliptical in cross section; glochids bright yellow; mature fruit usually dark purple or dark pink; [of coastal areas and also commonly cultivated]. |
| ............ ..........12 Glochid pattern generally of an adaxial crescent in the areole, i.e, glochids forming a dense fascicle in the upper portion of the areole, not widely separated throughout, exserted or not from the areole; spines yellow, sometimes with dark lateral banding; cladodes typically tuberculate with scalloped margins; [native, collectively widespread in coastal areas and also occasionally cultivated]. |
| ............ ............ 13 Cladodes spiny throughout, the spines 0-11 per areole, generally curved and spreading from the areole margins, the marginal spines usually strongly flattened at the base, then with 1-4 central spines, which are dark yellow and commonly with dark brown or black bands towards to base and middle of the spine |
| ............ ............ 13 Cladodes usually few-spined, spines mostly 0-3 per areole, generally straight, produced erect from the areole or only slightly spreading, usually rounded, slightly twisted, or only slightly flattened at base, yellow |
| ............ ..........12 Glochid pattern generally of a pin-cushion type, with the glochids widely separated and exerted from the areole; spines white with dark bases or yellow; cladodes not strongly tuberculate, the margins smooth not scalloped; [cultivated widely, and seemingly introduced in remote areas on barrier islands of SC, NC, and se. VA]. |
| ............ ............ ..14 Spines white, with red-brown bases |
| ............ ............ ..14 Spines yellow, with or without dark bases. |
| ............ ............ ....15 Cladodes rotund, elliptical or obovate in outline, obviously determinate |
| ............ ............ ....15 Cladodes elongate, ovate or narrowly ovate (lanceolate) in outline, appearing indeterminate as a result of the lengthening and narrowing of the cladode apex |