These spores look like little bean sprouts, suggesting that they started to develop before being mounted. This appearance is misleading, however. The spores are attached to cone like structures with elastic threads which are wrapped around the spores when moist and unravel when they dry.
The plant itself is also called "horsetail fern", though it is not a true fern. It comes from a group related to ferns which is now represented by a single genus but was once quite common and included giant forms now seen only as fossils. They are called "bottlebrush" because they tend to form unbracnched stems with numerous needlelike projections, thus giving it an appearance similar to a bottle brush.