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FIGURE 8. Development of asexual, bispore-producing C. coinpactum conceptacles described from specimens col- 

 lected in the northeastern Gulf of Maine. (A) Early sporangial mother cells and distinctive supporting cells (Septem- 

 ber-October). Eerfile disk (nemathecium) 100- 1 20 pm in diameter; it expands vertically, without primary calcification 

 (sporangia or intersporangial filaments), to form a fertile uncalcified cylinder. Initiated as meristem cells at 10-20 pm 

 of length, sporangia expand vertically, accommodated by growth in the surrounding calcified vegetative tissue. (B) 

 Later stage: sporangia over 100 pm in length with a thick, organic, apical wall or cuticle (to form spore release pore). 

 Here a decalcification "front" below and to the sides of the fertile cylinder is seen; cell crushing has yet to occur. Eight 

 to 12 vegetative cells have developed in the surrounding vegetative crust to allow sporangial growth. (C) SEM image 

 of an aborted conceptacle just prior to the stage shown in B (northern Labrador). (D) Later stage with further decalci- 

 fication; sporangial enlargement laterally and some crushing of surrounding vegetative cells. The overlying epithallial 

 cells have broken off to expose the conceptacle roof (white disks seen from surface). A later surface view of this stage 

 is shown in Figure 9C, D. (E) Light microscopic image of mature conceptacle at full, mature dimensions (December- 

 January), with decalcification and crushing of lateral and underlying vegetative cells, and spores forming inside the 

 sporangia. A, B, and D were drawn from microtome sections of winter plants. C is a SEM image of a calcified, frac- 

 tured section. E is a decalcified and stained microtome section. All images are at the same scale, indicated by the bar. 



