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