Love is in the Air- Plant Reproduction

Blireiana Flowering Plums produce showy, double fragrant flowers in early spring.

One of my favorite classes when I attended Cal Poly San Luis Obispo was Plant Taxonomy. On the surface the subject sounds a little dry but the professor was all about plant reproduction which is quite exciting and more varied than you think. So with Valentine’s Day upon us here are some interesting facts about how plants get together.

If you’re like me you’ve caught a case of pre-spring fever. How can we help it when the flowering plums are covered with hundreds of blossoms, the saucer magnolia flowers are opening and the flowering quince are in full bloom? When I lived in Bonny Doon, my Blireiana Flowering Plum was always in bloom around the time of Valentine’s Day. I would have my picture taken under it posing with my presents. Here’s a reminder of how flowering plants reproduce.

Blireiana Flowering plums are in the rose family. They have perfect flowers meaning that they have both male and female reproductive parts on the same flower. They depend on pollinators like bees, moths and hummingbirds to transfer pollen.

Some flowering plants like oaks, spruce, corn, pumpkin and birch trees have separate male and female flowers on the same plant making them self-pollinating. They are monoecious meaning “single house”.

Dioecious plants have male flowers on one plant and female flowers on another. Examples are myrica, gingko, juniper, spinach, walnut, asparagus and ash.

Daphne odora ‘Aureomarginata’

Blooming at this time of year is the fragrant Daphne. How does it reproduce? Daphne have powerfully fragrant flowers filled with nectar to attract pollinators such as bees and other insects. They are monoecious.

Hellebores fall into this category also (kinda) Hellebore flowers are also protogynous, which means that the carpels (female reproductive organs) nature before the stamens ( male reproductive organs). This encourages cross-pollination. But although hellebores are protogynous, they are also self-fertile. Seems like they have all the bases covered- they are never out of bloom starting in early winter and blooming into late spring.

Looking around my little garden I enjoy the cyclamen flowers at this time of year also. Cyclamen are mostly monoecious. Many fruit trees fall into this category, too, like almonds, apricots, cherries, nectarines, peaches and prunes.

Not all flowers are large and brightly colored. Some flowering plants, like grasses, have flowers that are tiny and may even be green.

Other plants have no flowers at all. Mosses reproduce from male and female mosses which produce spores. Conifers produce two type of cones on the same tree. Wind blows the pollen to another cone which combine to make a baby conifer which lives in a seed inside the cone.

So on this Valentine’s Day, take a minute to appreciate plants and all they provide for us.

Phenology and Climate Change

Check your lilac for mouse-ear sized leaves.

What’s that wet stuff coming from the sky? Hopefully by the time you’re reading this we will have gotten some much needed rainfall. I wanted to research the latest scientific papers on how climate change is impacting our gardens.

Plants have adapted over millennia to their growing conditions. The abrupt differences due to changing climate forces plant to migrate or go extinct. When temperatures increase plants bloom earlier creating the potential for timing mismatch between pollinators and plants.

Phenology – not to be confused with phrenology which claims that bumps on the head predict mental traits – is the study of key seasonal changes in flowering times, emergence of insects and migration of birds from year to year. When do they occur each year? Phenology is a real science that has many applications. In farming and gardening, phenology is used chiefly for planting times and pest control. Predictions for fire season are based on factors pertaining to weather as well as plant growth. Certain plants give a cue by blooming or leafing out that it’s time for certain activities such as sowing particular crops or insect emergence and pest control. Often the common denominator is the temperature.

Websites like USA National Phenology Network at http://www.usanpn.org/ offer lots of information on the subject. The US Global Change and Research Program released the first 14 indicators of climate change. Among these is the Start of Spring indicator on this website which reflects the accumulation of heat sufficient to initiate leafing and flowering in temperature sensitive plants. Your own observations via Nature’s Notebook will help contribute to this research.

How will this spring compare to normal? This site is regularly updated with data submitted by gardeners like you. Starting this year they are adding a new aspect of spring- the end of spring. They will forecast the activity of plants that bloom at the tail end of the season. This information will help us understand the length of the spring season in a particular year as well as whether a location that seas an early start to spring also see an early end.

Indicator plants are often used to look for a particular pest and manage it in its most vulnerable stages. They can also be used to time the planting of vegetables, apply fertilizer or prune. Here are some common garden plants and what they indicate:

When daffodils begin to bloom, sow peas.
When dandelions bloom, plant spinach, beets and carrots.
When lilac leaves are the size of a mouse’s ear, sow peas, lettuce and other cool-weather crops.
When lilacs are in full bloom, plant beans.
Once lilacs have faded, plants squash and cucumbers.
When apple trees shed their petals, sow corn.
When dogwoods are in full bloom, plant tomatoes, peppers and early corn.
When bearded iris are in bloom, plant peppers and eggplants.
When locust and spirea bloom, plant zinnia and marigolds.

When forsythia and crocus bloom, crabgrass is germinating. When this happens the soil temperature at a depth of 4 inches is 55 degrees. Treat with an organic pre-emergent.
When crocus bloom, prune roses and feed your lawn.
Mexican bean beetle larvae appear when foxglove flowers open.

Record your own observations. Another great site is National Sustainable Agriculture Information Service at http://attra.ncat.org. Sites like these can also help you design orchards for pollination and ripening sequence, design for bee forage plantings, design perennial flower beds and wildflower plantings as well as plantings to attract beneficial insects and enhance natural biological control. How cool is that?