The Pine Lily

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The pine lily (Lilium catesbaei) is one of North America’s finest species of lily. It produces the largest flowers of the genus on this continent and to see one in person is a breathtaking experience. The pine lily is endemic to the Southeastern Coastal Plain where it prefers to grow in mesic to wet flatwoods, wet prairies, and savannas. Though it enjoys a relatively wide distribution, today it rarely occurs in any abundance.

The pine lily’s rarity may be a relatively recent status change for this wonderful plant. Historical records indicate that it was once quite abundant in states like Florida. Today it occurs in scattered localities and predicting its presence from year to year has been a bit tricky. Indeed, the pine lily appears to be very picky when it comes to growing and flowering.

One aspect of its biology that might lend to its limited appearance is the fact that it can remain underground in a dormant state for years. Like other members of this genus, the pine lily emerges from a bulb. This underground storage structure is small by lily standards, which means that most pine lilies are operating on marginal stores of energy in any given year.

Some have estimated that individual bulbs can remain dormant for upwards of 5 years before the right conditions for growth flowering present themselves. Of course, such dormancy can be a nightmare for proper conservation of such a unique plant. Aside from the individual flower borne at the tip of a long, slender stem, the rest of the plant is very dainty. In fact, its flowers can be so heavy compared to the rest of the plant that some stems simply topple to the ground before they can set seed. The slender stem, small leaves, and tiny bulb equate to a small operating budget in terms of energy stores. That being said, we are starting to get a clearer picture of what pine lilies need to thrive and it all comes down to fire.

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The key to acquiring enough energy for growth and reproduction appears to be a proper amount of sunlight. Without it, plants languish. This is where fire comes in. The pine lily lives in a region of North America that historically would have burned with some frequency. Wildfires sweep through an area, burning away competing vegetation like saw palmetto (Serenoa repens) and clearing the ground of accumulated debris like sticks and leaves. By burning away the competition, fire creates open areas where delicate plants like the pine lily can eke out an existence. Indeed, research has shown that pine lilies produce more flowers and seed immediately following ground-clearing burn followed by a subsequent decline in flowering and seed set as the surrounding vegetation begins to grow back.

If a pine lily does have enough energy to flower, then one of the most stunning flowers in all of North America is presented with its face towards the sky. Its 6 large petals are brightly colored and taper down into what looks like tiny tubes. Nectar is produced within these tubes and, coupled with the bright coloration, attract numerous insect visitors.

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Not all insects are capable of successfully pollinating such a large flower. In fact, it would appear that only a couple of species take up the bulk of the pollination of this incredible plant. As far as we know, the Palamede swallowtail butterfly (Papilio palamedes) and perhaps the spicebush swallowtail (P. troilus) are the only species large enough to properly contact both anthers and stigma while feeding at the flowers. The large wingspan of these butterflies do all of the work in picking up and depositing pollen. All other insects are simply too small to adequately achieve such feats.

Though we still have a lot more to learn about the pine lily, what we do know tells us a story that is repeated for fire-dependent ecosystems throughout the world. Without regular disturbance from fire, biodiversity drops. The pine lily is not alone in this either. Its fate is intertwined with countless other unique plant species that call the coastal plains their home.

Photo Credits: [2]

Further Reading: [1] [2] [3]

Taxonomic Discoveries: My Version of the Butterfly Effect

Witnessing a giant swallowtail (Papilio cresphontes) in flight is an incredible experience. It is the largest species of butterfly found in the US and Canada and with its yellow and black wings, it is impossible not to take pause and watch it flutter around the canopy. I will never forget the first time I saw one as a child. It was one of those moments that solidified my obsession with the natural world. Fast forward a few decades and now I can't help but ponder what kind of gardening I would need to do to attract these incredible insects to my yard. What I discovered surprised me to say the least. I had to plant something in the citrus family. 

We are all familiar with the fruits of various Rutaceae. This family contains the genus Citrus, providing humanity with oranges (C. × sinensis), lemons (C. × limon), grapefruits (C. × paradisi), and limes (mostly C. aurantifolia). These are largely tropical and subtropical trees, struggling to hang on anywhere temperatures dip below freezing regularly. How on Earth was a butterfly whose larva specialize on this family flitting around in temperate North America? What's more, reports place this species as far north as southern Quebec. I was obviously out of the loop on the taxonomic affinities of this family.

A little detective work turned up some surprising results. Temperate North America does in fact have some representatives of the citrus family. They are a far cry from an orange tree but they are nonetheless relatives. This inquiry actually solved a bit of trouble I was having with some riparian trees in my neck of the woods. As some of you probably know, trees are not a strong point of mine. I had encountered a few small woody things with compound leaves of three and dense clusters of greenish flowers. At first I thought I had found a rather robust poison ivy specimen but closer inspection revealed that wasn't the case.

Instead I had stumbled across something new for me - a common hoptree (Ptelea trifoliata). This cool looking tree is one of the giant swallowtails larval host trees, making it a member of -(you guessed it)- the citrus family. More often this small tree grows like a shrub with its tangle of multiple branches but they can reach some impressive heights, relatively speaking of course. Trees topping out at a height of 5 meters are not unheard of. Another common name of this tree - wafer ash - hints at its superficial similarity to a Fraxinus. Its compound leaves and wafer-like samaras are a bit of a curve ball for northerners like myself. It has a rather wide and patchy distribution throughout North America, and many subspecies/varieties have been named.

Common Hoptree ( Ptelea trifoliata  )

Common Hoptree (Ptelea trifoliata )

The other bit of this taxonomic journey involves another small tree, although this time I was better acquainted. Another host for the giant swallowtail is the prickly ash (Zanthoxylum americanum). It is interesting to note that both of these northern host trees superficially resemble ashes but I digress. The prickly ash is also small in stature and is most often found in thickets consisting of its own kind. As its common name suggests, you wouldn't want to go barreling through said thickets unless you wanted to donate some blood. It is well defended by sharp prickles on its stems. It does produce fruit but they are rather small and berry-like (technically follicles) and are distributed far and wide by birds.

Prickly Ash (  Zanthoxylum americanum   )

Prickly Ash ( Zanthoxylum americanum )

Both trees are rather aromatic. They produce volatile oily compounds like most of the family, making them smell quite pleasant. Their small size makes them interesting specimen trees for anyone looking for something unique to put in a native landscape. What's more, they host a variety of other larvae as well, including those of the spicebush swallowtail butterfly (P. troilus).

Together, these two species are the most northerly representatives of the citrus family, making them quite special indeed. I am happy that my interest in attracting giant swallowtails to my property resulted in a fascinating dive into the geography of this interesting family.

Photo Credits: [1] [2] [3]


Further Reading: [1] [2]