Plants can be so uncooperative. The Equisetum (3 species) in our glasshouse was most untimely and no strobili were available (other than pickled) for lab. Probably that was OK because my way too many of my students were in an uncooperative, non-observational mood. They broke all the "make observations" rules. Clicking pictures of things they didn't study is the worst, especially when the fossils are too small to see anything. You might as well turn in an image of green water in a test tube and label it "Chlamydomonas"; it's been done, and it pretty well demonstrates that the student in question didn't observe a damned thing. This is the down side of digital. It promotes a superficial, fast and easy approach, a non-learning approach. The don't pay attention attitude was so bad that at the end of class TPP had to re-sort all of the microscope slides because students didn't pay enough attention, read the labels, and match them with the correct slide trays. Pure sloppiness. Now of course this was not universal; the gap just widens between the attentive and the inattentive. It makes it easy to sort the sheep from the goats, which is part of my job, but you wish you had enough time to promote better study habits.