Definition of "sporangium"

Scientific explanations include that exposure to light, lack of moisture or absence of food can cause sporangia to form from the plasmodium. At least one of these three conditions has been present every time I've seen sporangia form.

1993, Sally Stenhouse Kneidel, Creepy Crawlies and the Scientific Method: Over 100 Hands-on Science Experiments for Children, page 81

Asexual reproduction by the production of a bud in place of a sporangium is not uncommon.

2000, Peter R. Bell, Alan R. Hemsley, Green Plants: Their Origin and Diversity, page 161

The sporangia, however, are much larger: 3–4 mm long 0.7–1.1 mm in diameter versus only 1–1.5 mm long 0.5–0.8 mm in Corynepteris, and are characteristically banana shaped with a pair of elongate annuli.

2009, Edith L. Taylor, Thomas N. Taylor, Michael Krings, Paleobotany: The Biology and Evolution of Fossil Plants, page 416