Nature and development of plants . duction of a powdery mildew: A, meeting of themale, an, and female, 0, gametangia. B, fertilization, the male gamete, m,is seen approaching the female. C, section of young ascocarp showing theearly germination of the gametospore, which has become surrounded byhyphae derived from the mycelium. D, later stage, the gametospore hasdeveloped several cells and the terminal one is being transformed into anascus, as.—After Harper. 214 CLOSED TYPE OF ASCOCARPS contact of these organs permits the male gamete to pass overand fuse with the female (Fig. 147, D). The growt
Nature and development of plants . duction of a powdery mildew: A, meeting of themale, an, and female, 0, gametangia. B, fertilization, the male gamete, m,is seen approaching the female. C, section of young ascocarp showing theearly germination of the gametospore, which has become surrounded byhyphae derived from the mycelium. D, later stage, the gametospore hasdeveloped several cells and the terminal one is being transformed into anascus, as.—After Harper. 214 CLOSED TYPE OF ASCOCARPS contact of these organs permits the male gamete to pass overand fuse with the female (Fig. 147, D). The growth of thegametospore forms a limited number of cells, one or more ofwhich develop into asci (Fig. 147, C, D). As in Penicillium,this growth becomes enveloped by a mass of hvphae that originatefrom the mycelium. These ascocarps appear at maturity asblack specks and in the majority of forms they are provided withhair-like outgrowths that are very regular and characteristicof the genera (Fig. 148). The ends of these hairs are rather. Fig. 148. Forms of ascocarps found among the powdery mildews: A,Phyllactinia with needle-like appendages enlarged at the base. B, Micro-sphaera, appendages dichotomous at apex. C, Uncinula, appendages coiledat apex. D, Erysiphe without appendages and crushed to show escapingasci. E, an ascus containing six ascospores. mucilaginous and may assist in the dissemination of the asco-carps. The ascospores are resting spores adapted to enduringdrought and cold as in Penicillium, which they resemble in theirdischarge and germination. 87. Forms with Slightly Opened Ascocarps.—Several ordersof the Ascomycetes are distinguished from the preceding groupby the formation of ascocarps that are slightly open ( Figs. 151 :152, B). Tn this way, provision is made for the discharge ofthe ascospores without the decay of the ascocarp. Only two ofthese orders can be noticed. DEVELOPMENT OF PLANTS 215 88. Order e. Sphaeriales or Black Fungi.—This is the largestgroup of
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