| 31. | Each flower has generally four hairy green sepals and four yellow petals grouped together on one side of the involucre.
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| 32. | The genus is closely allied to " Senecio " and can be distinguished principally by details of the involucre.
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| 33. | There are also yellow ray florets, but they are so short they may be nearly invisible inside the involucre of phyllaries.
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| 34. | The inflorescence is a solitary phyllaries which are fused at the base, making the involucre a rounded cup with pointed lobes.
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| 35. | The involucres also show a spectrum from thin, leafy lobes that display distinct veins to thick lobes with no distinct venation.
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| 36. | A predominant number of the fruits possess more dissected involucres, some having simple spines, while others have both simple and branched spines.
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| 37. | The involucre is above and supported by bract-like modified leaf structures ( usually in pairs ) called cyathophylls', or cyathial leaves.
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| 38. | The only other subgenus ( " Riella " subg . " Riella " ) bears smooth involucres that lack these wings of tissue.
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| 39. | The inflorescences are pseudo-umbels, flat-topped or rounded flower clusters, each pseudo-umbel with an involucre of four or six decussate bracts.
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| 40. | "Hymenostephium " is characterized by the relatively slender habit of the plants, 1-2 seriate involucres, and relatively small heads of flowers.
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