Flora of North America species comparison

± diffuse.

short, fleshy, enlarged taproots, basally ± 1/3–1/2 of stem diam.

spheric or ovoid (cylindric in old plants), deep-seated only when young, sometimes flat-topped, 5–15(–25) × 5.5–8.5(–15) cm;

tubercles (10–)15–30(–40) × 8–15 mm, firm;

areolar glands seasonally conspicuous;

parenchyma not mucilaginous;

pith 1/3–1/2 of lesser stem diam.;

medullary vascular system present.

deep-seated, aerial parts inconspicuous, flat-topped to hemispheric (to ovoid or spheric in horticulture), almost completely withdrawing into substrate when desiccated, (2.4–)5–9 × 1.5–4.7 cm, above-ground portion 1–6.5(–9);

tubercles 5–9(–12) × 4–6(–7) mm;

areolar glands absent;

parenchyma not mucilaginous;

druses present, largest druses lenticular, 0.3–0.5 mm diam.;

pith 1/5–1/3 of lesser stem diam.;

medullary vascular system not recorded.

7–20+ per areole, usually whitish, straw colored or horn colored to grayish tan, sometimes pale pinkish gray when fresh, tips dark red to dark brown, larger spines often extensively tipped chestnut, blackish purple, or black;

radial spines 6–16(–20) per areole (commonly 5–7 on immature plants), 11–35 mm, nearly as large as the central spines, often longer, 0.8–1.2 mm diam.;

subcentral spines 0–2 per areole;

central spines 1–4 per areole (0–1 on immature plants), abaxial (or only) spine porrect or slightly ascending, larger spines rigid, straight on older plants in eastern populations (strongly curved and/or hooked in some immature plants and young adults of western populations), one 23–34 mm, others, if present, 12–50 × 0.3–2 mm.

(12–)15–20(–25) per areole, white with brown tips (quickly weathering to gray) or the adaxial spines per areole dark gray-brown throughout; all radial spines or 1–3 adaxial spines sometimes interpreted as central, laterally compressed at base, 6–13 × (0.1–)0.2–0.3 mm;

subcentral spines 0(–3) per areole;

central spines 0(–3) per areole, appressed, straight, ± equal, 9.5–13(–15) × 0.2–0.3 mm.

nearly apical, (38–)45–64 × (32–)50–73 mm;

outer tepals minutely fringed;

inner tepals ca. 20 per flower, dark golden yellow, pale greenish yellow, translucent dull yellow, or saffron yellow, proximally reddish, often bronze tinted proximally or in vague midstripes, sometimes turning entirely pinkish bronze, 23–36 × 5–11.5 mm;

outer filaments reddish or orange;

anthers pale to bright yellow;

stigma lobes 6–11, cream to creamy pink, yellow, or orange-yellow, 3–7 mm.

nearly apical, 18–25 × 20–34 mm;

outer tepals fringed;

inner tepals 22–27 per flower, bright rose-pink or magenta, proximally paler, 10–17 × 2–4 mm;

outer filaments colorless or white to rose;

anthers orange-yellow;

stigma lobes (4–)5–6(–7), white, cream, or pale pink, 1–3 mm.

green, fusiform-cylindric, (35–)40–50 × (12–)13(–15) mm, slimy;

floral remnant deciduous, leaving a concave abscission scar.

green, spheric or obovoid, (3.5–) 5–8(–10) × 3–6 mm, quickly drying;

floral remnant usually persistent.

bright reddish brown, narrowly reniform-cylindric to reniform-obovoid or comma-shaped, 2.3–3.5 mm, smooth, shiny (anticlinal cell walls forming a conspicuous reticulate color-pattern, but not visibly protruding).

dark brown, spheric, 0.9–1.1(–1.2) mm, pitted.

= 22.

= 22.