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Key to Celtis

Cannabaceae

Celtis

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(c) Sinani, Thomaz Ricardo Favreto - CC-BY
1 Branches armed with nodal thorns, (1-) 5-20 (-55) mm long.
(c) Sinani, Thomaz Ricardo Favreto - CC-BY
  2 Thorns usually single, usually < 8 mm long and rarely bearing leaves; styles 3-4.5 mm long; fruit 7-12 mm in diameter; pyrene 5-7 mm long, coarsely reticulate
(c) Wong, Michelle - CC-BY
  2 Thorns usually paired, often > 10 mm long and then often bearing leaves; styles < 1 mm long; fruit 6-7 (-8) mm in diameter; pyrene to 4 mm long, with low, alveolate-reticulate sculpturing
(c) Wong, Michelle - CC-BY
1 Branches unarmed.
    3 Leaves thick, very glossy above; bark remaining smoothish, lacking protuberances; [rare exotic]
    3 Leaves thin, dull or glossy above (glossy normally only in sun leaves); bark developing wartlike corky protuberances on larger individuals; [collectively common natives].
© Adam Black
      4 Leaf lower surface densely white-pubescent; [TX]
      4 Leaf lower surface glabrous or with inconspicuous hairiness mainly on the veins; [collectively widespread].
        5 Leaf blades (fully-formed leaves subtending fruits) 7-12 cm long, the longer side with 23-40 teeth, the shorter with 12-27 teeth; secondary veins 5-8 on each side of the midvein, the basalmost reaching the leaf margin at a point 1/3 to ½ the length of the leaf above the base; fruits 8-10 mm long
        5 Leaf blades (fully-formed leaves subtending fruits) 2.0-8.5 cm long, each side with 0-15 (-23?) teeth; secondary veins 3-5 on each side of the midvein, the basalmost reaching the leaf margin at a point 1/3 to 2/3 the length of the leaf above the base; fruits 5-10 mm long.
          6 Leaf blades 2-4.5 (-7) cm long; upper leaf surface harshly scabrous; leaf apex obtuse to acute (rarely nearly acuminate); fruit (5-) 8-10 mm in diameter; [LA and OK southwestwards]
          6 Leaf blades (2-) 5-8 (-15) cm long; upper leaf surface smooth or slightly scabrous; leaf apex acuminate to acute; fruit 5-8 mm in diameter; [collectively widespread].
             7 Plants shrubs or small trees, to 7 m tall, with ascending trunks and horizontal or arching leaders; bark often nearly smooth (sometimes with corky warts near the base or around wounds); leaf undersurface glaucous or pale green, usually distinctly lighter than the upper surface; flower stalks usually hairy (puberulent); twigs usually moderately to densely hairy (sometimes glabrous); anthers small and indehiscent, pollen malformed and generally sterile (< 10% of the grains stainable with acetocarmine)
             7 Plants usually trees, to 30 m tall, typically single-trunked, with erect leaders; bark with corky warts on trunks and major branches; leaf undersurface usually bright green, little if at all paler than the uppersurface; flower stalks glabrous (rarely with a few hairs); twigs glabrous or sparsely hairy; anthers well-developed, dehiscent, pollen copious, regular, and fertile (> 95% of the grains stainable with acetocarmine).
(c) Wong, Michelle - CC-BY
               8 Leaves subtending fruits with margins entire or with 1-2 teeth 0.5-1 mm long on one side only (leaves of juvenile plants or of vigorous leader shoots may be more strongly toothed)
               8 Leaves subtending fruits with margins with 2-15 teeth 1-2 mm long on each side