about jacob

Jacob Suissa is a scientist from Bethesda, Maryland who studies plants. He is a professor at the University of Tennessee, Knoxville. Growing up, he spent most of his time playing sports or wandering around the woods in his friend’s backyard. Jacob liked dissecting and investigating plants, but he didn’t realize he wanted to study them until he was in college at the University of Vermont and started working as a gardener for his university and spent a lot of time thinking about plant anatomy. That led him to pursue his PhD in Evolutionary Biology at Harvard, where he continued his studies of plants. Jacob loves to hike, swim, run, play sports like basketball, and do jigsaw puzzles.

Art and Science

Jacob says, "I believe that art and science are two sides of the same coin. They are ways in which we, as humans, can make sense of the world. Integrating these two concepts is important for inspiring and educating. Plants—with their ever-varying shapes, colors, and structures—provide a perfect medium for displaying this integration. I take photos of plants to display their artistic beauty and intricate scientific structure in hopes to inspire people to enjoy and appreciate plant life." You can look at some of his nature photography here!

A couple of years ago, Jacob published the results of a study investigating the reproductive strategy of a fern called the sensitive fern. These ferns are native to much of eastern North America and got their name because of the way the fronds die back quickly after a frost. While we often think of plant reproduction in terms of flowers, pollinators, seeds, and fruit, not all plants reproduce that way. Some plants have cones, like pines and cedars. Ferns, on the other hand, have something called spores--tiny packets of genetic information that typically grow in clumps on the underside of fern fronds/leaves. Most ferns grow new fronds in the spring (you may have seen these, they're often called "fiddleheads"), and their spores grow on these new fronds until late summer or early fall when they are blown away by the wind to hopefully grow somewhere else. 

The sensitive fern does things a little differently! The sensitive fern is dimorphic, meaning it has sterile fronds that have no spores on them, and fertile fronds that look completely different and house the spores (ferns like our native sword fern, however, have spores on all their fronds). These fertile fronds die and hold on to the spores for up to 8 more months, then release them the following spring. This delayed spore release is a very unique form of fern reproduction and botanists have known about it for over 100 years and developed some theories on why it exists, but until recently have not really understood how it works. Jacob's research helped explain this.

Jacob used three strategies to solve this problem--field observations (looking at sensistive ferns in the wild), growth chamber manipulations (growing sensitive ferns under varying conditions in captivity), and scanning electron microscope imaging (taking very zoomed in photos of cells in the reproductive tissues to see what structures may be involved and how they might work). 

He found that the dead tissues of the fertile fronds respond to changes in humidity in the air and actually move. When they are wet, they close tightly, but as the humidity drops, they unfurl and reveal the spores. While we tend to think of plants as pretty stationary, movement in plants is not totally uncommon. Most of us are familiar with Venus fly traps--this movement happens in living tissues rather than dead ones. In ferns, many species besides the sensitive fern also use tissues that move in response to low humidity--they hurl their spores into the wind like a catapult (see a cool video of this below!). The sensitive fern, however, uses a very different mechanism of unfurling than these other ferns. It's much more similar to the way that pine cones open up under dry conditions to expose their seeds (see video below). The similarity to pine cones is interesting, because ferns and pine cones are not closely related. This tells Jacob that this strategy of seed/spore dispersal has evolved independently several times. This is called "convergent evolution". 

Jacob is passionate about science communication. He has an Instagram account called "Let's Botanize!" that explains plants an botany in a way that is interesting and accessible to non-experts. Check out this video he made to explain this study on sensitive ferns!