Checking the Draba and Leavenworthia

I gave the barrens a close examination and found the winter annuals to be doing extremely well this year.  This Leavenworthia uniflora rosette has a healthy cluster of leaves and at least four flower buds nestled in the center of the whorl.  That’s quite an improvement over what I found last year.  The difference is the result of nearly no snow cover this winter, while snow covered the ground most of the winter last year.  Leavenworthia germinates in the fall and grows throughout the winter.  Snow cover blocks the sunlight and slows the growth of the plant.  After an especially snowy winter, both plant numbers and size are decreased.

This is where the Leavenworthia grows.  It sinks its long tap root as best it can into gravelly limestone soil.  A well anchored root is essential to survive in a soil that alternately freezes and thaws through the winter.  As the soil freezes, it expands and pushes upward.  Plants not anchored to the soil below the freeze line are pushed up and left stranded on the surface when the soil thaws and falls back into place.

Plants that survive the rough winter conditions will flower in the spring.  Seed will mature before the poor soil dries out in the summer sun.

Draba cuneifolia has a life cycle like that of the Leavenworthia.  Its small rosette of leaves is working hard to turn sunlight into energy for that all important process of producing seed for next year’s population.  At this stage, the tiny plants are almost impossible for a person to see from a standing position.  It’s necessary to get your eyes close to the ground to find these plants.  The cedar needles and dried grass stalks are an indicator of the plant’s diminutive size.

The Drabas are also quite numerous this year.  With luck, there should be a tremendous amount of seed produced.

Still, the plants growing in the barrens don’t come close to matching the tremendous growth displayed by my container bound population.

The Drabas are so crowded together in the container that other plants have trouble competing.  The small pointy leaved plants are Chickweeds that are having trouble breaking through to the sunlight.

Where the Drabas are not so crowded together, the individual plants have attained a larger size.  In these areas, Leavenworthia is able to find room to grow.

The Leavenworthia is having trouble maintaining itself in the container dominated by Draba.  I have already prepared a new container that will be solely dedicated to Leavenworthia.  When I originally put these two species together, I was expecting them to behave as they do in the barrens and just produce a scattering of plants.  It’s obvious now that I was mistaken.  I’ve been growing these plants in containers for several years and seem to learn something new about their growth habits every year.

Seed Harvest

This was a rough year for the small winter annuals that live in the barrens.  These plants begin their growth in the late fall and flower in early spring.  They grow as long as sunlight is available, but this year, frequent snowstorms kept the ground covered for most of the winter. When winter finally ended, the plants had developed to just a fraction of their normal size.  Small plant size corresponds into a reduced seed crop.  For a plant that dies following seed production, fewer seeds likely mean a reduced population size the following year.  Several bad years in a row could eliminate a population.

My container grown plants came through the year in excellent shape.  Unlike their wild counterparts, these plants displayed the best the species can produce.  They proved an excellent example of how slightly different growing conditions can make a big difference in results.  The Leavenworthia uniflora shown here are as robust as any I have ever seen.

I grow plants in containers so that I can observe the daily changes in plant development.  A secondary goal in raising the more rare species is to produce seed that can be used to augment what is being produced naturally.  The original seed for these plants came from the barrens of Blue Jay Barrens.  Extra seed produced in containers is returned to the site of the wild population. 

The fruits are stuffed full of seeds.  This is about an average yield for the container grown plants.  Those in the barrens only produce four seeds at best.

I’ve been collecting seeds from the container for a week now.  The photo above illustrates a typical day’s harvest, a total of about 40 fruits.  I harvest the fruits just as they begin to split and expose the seeds.  I miss plenty, so there are more than enough seeds left in the container for next season.

Harvested fruits are left to dry for a few days.

When the seeds have completely dried, they are stored in an envelope until planting time.

Once I harvest the last of the seeds, I’ll take them out and scatter them on the barrens.  Leavenworthia seeds need a period of hot weather to allow them to break dormancy and germinate in the fall, so it’s important to get them planted while there is still plenty of summer yet to come.  I’ve also found that it’s best to plant seeds at the same time they would naturally be dropping from the plant.  That way they are naturally going to get the treatment they need for germination.  Hopefully, the coming winter will be more conducive to Leavenworthia growth and the barrens will produce a record crop next year.

Problem Weed in Pot

I had this idea that I could get ahead of the weed infestation in my winter annual pot by spraying when the weeds first appeared in the fall. This pot remained consistently plant free until about a week ago. That’s when I noticed a flush of green as things began to germinate. I decided to wait a few days to allow the plants to become more identifiable before spraying with herbicide.

The primary undesirable plant was chickweed, which is easily eliminated by a weak solution of glyphosate. A closer examination revealed a problem with my well thought out plans. I could see plants in the mix that were definitely not weeds. Spraying was removed from my list of weed control options.

This is Draba cuneifolia, a small winter annual that will grow through the winter and flower sometime early next April. At least I’m assuming it to be Draba cuneifolia. It’s hard to identify the Drabas when they’re this young. The only other option is Draba reptans, but that species usually germinates a little later in the fall and doesn’t reach this size until late winter. Either way, this is one of the uncommon Draba species that I’m trying to cultivate in this pot.

I persuaded President Lincoln to enter the frame for a size comparison to illustrate the tiny size of these seedlings. I took the time to weed this small space using a pair of tweezers, so things were clear enough to see the Drabas. At this stage, these are very fragile plants that are easily damaged, so it’s a rather delicate operation to remove weeds without compromising the integrity of the Draba root system. During the next few months they’ll have to withstand heavy rains, deep snow and freezing temperatures. It’s amazing that any survive the ordeal.

There are still a lot of weeds left to destroy in this pot. I may have to modify some tiny tools to make the weeding process a bit easier. I wonder if this is what’s meant by micromanagement.

Leavenworthia uniflora, another uncommon native winter annual, is also actively growing in the pot. Leavenworthia are a little more robust that the Drabas, but they’re still awfully small. Soil in this pot mimics as closely as possible the conditions found on the barren sites where these plants normally grow. That means there should be some Draba and Leavenworthia germinating out in the barrens. I’ve been looking, but I’ve yet to find any. The problem is that, even though I try to harvest as much of this seed as possible, the concentration of plants and the amount of seed falling to the soil within the pots is probably hundreds of times greater than what is found in any of the natural barren openings. You would need to search thousands of square feet of barren areas to find the same number of plants growing in this one pot. What I’m trying to convey is the difficulty of finding plants this small out in a natural field.

I guess I’ll just have to take part of a nice sunny day and tweeze the weeds out of this pot. I’m trying to produce enough seed so that next year I can plant a Draba/Leavenworthia bed. I should probably get the soil for that bed in place right away so I can get an early start on weed control. Tweezing weeds out of an 18 inch diameter pot is bad enough. I certainly don’t want to do the same thing to 30 or 40 square feet of bed.

Winter Annuals

Some of the barrens lost their cover of snow yesterday, although they’re probably covered again by now. I took advantage of the opportunity to check on the progress of some of the winter annuals. This mix of Leavenworthia and Draba looks in pretty good shape despite being partially covered by cedar needles deposited by the melt water.

This is a pretty tough place to survive. Rain, snow and rocky ground make it difficult for small plants to survive, but those aren’t all of the challenges.

A deer could mash dozens of these little plants with one step. Fortunately deer don’t have any reason to congregate on the rocky barrens, so the only damage they cause is when they stroll through.

Something made a chipmunk sized hole and scattered dirt in a broad circle. Once covered, the winter annuals will not survive. Disturbed soil on these sites can result in the death of plants, but it is also a way that dormant seeds find their way to the surface to germinate.

The excessive moisture has caused the Nostoc population to explode. It is unlikely that small plants trapped beneath the Nostoc will survive.

Despite the hardships, the plants are looking pretty good so far. There will be more losses before growing conditions stabilize, but there should be plenty of plants left to produce seeds for the next generation.