41. It produces a thick thallus and ( usually ) lacks rhizohyphae and ascending thallus margins. 42. The whole thallus sometimes intricately branched throughout. 43. Their abundance is conspicuous when the thallus is sectioned and examined under a dissecting microscope. 44. Pigmentation is weak near base of thallus . 45. The species'name thus refers to its uncommon dark gray colouration of its thallus . 46. The term thallus is also commonly used to refer to the vegetative body of a lichen. 47. This stage usually grows as a thin cell of the thallus usually contains just one chloroplast. 48. Depending on whether the thallus morphology. 49. In a classification presented by level of organization of the thallus , there are seven orders: 50. The thallus cells often contain more than one chloroplast, as opposed to other hornwort genera.
