MONO MONDAY

It's Mono Monday and the Challenge theme is Sphere or Ovoid.
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This is a Golden Barrel Cactus (Echinocactus grusonii); although it doesn't look too "golden" in this photo...but check out the extra for a full color sample.
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This plant is native to Mexico but this colony thrives in the Mitchell Park Conservatory in Milwaukee.  Clearly it's a desert dweller and is well protected by an army of spines meant to deter individuals from taking a bite or two of its water rich interior.
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Obviously, the spines are for defense; the fluted/accordian-like nature allows the plant to swell during high water times without bursting or shrink in low water times without breakage.  It's has a hard waxy layer that prevents/retards evaporation and it's the stem of the plant that does the photosynthesizing. The needles are really modified leaves that no longer photosynthesize.
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BEST IN LARGE.