Bluebonnets in the fall.

Walking at dawn in the fall in Texas the yellows and golds and reds of the grasses and leaves tend to dominate.

Fall sunrise in Texas

But look closer, below the red and yellow grasses, and there are round, bright green seed leaves of Lupinus texensis– the Texas bluebonnet. After the heat of summer and the fall rains, around September or October, these emerald gems appear close to the ground. Soon afterwards, especially if there is more rain, the palmate leaves with their pointed hairy leaflets appear. On a morning with heavy dew the moisture collects on these leaves so that they shimmer like silver in the first rays of light, collecting little pearls of moisture at the base of the leaflets.

Dew decked bluebonnets in fall.

As the seedlings of these annuals grow they send down roots that have nodules. As members of the family Fabaceae they form symbiotic relationships with bacteria that fix gaseous nitrogen for the plant. This nitrogen gets passed on into the soil enriching it for other plants. In return the bacteria get carbohydrates from the plant.

Through winter storms these small green leafy rosettes wait for spring and the chance to flower. With good fall and spring rains fields of them will appear around March and April. The spike inflorescences of multiple blue flowers are easily identified as belonging to the pea family with the banner, wing and keel forming each flower.

Field of bluebonnets in Texas spring

Annual Pennyroyal

Hedeoma acinoides has appeared in abundance after the inch of rain this past weekend.  

Blooming for a short time in the spring it is a delightful miniature spring annual.  Only an inch or three high, in these pictures, it has created delightful little patches that look like miniature forests.

Plant identification books such as Marshall Enquist’s Wildflowers of Texas say it can be up to 8 inches.  Common in the rocky limestones of the hill country this member of the Lamiaceae or mint family has a minty smell if you crush the leaves a little.

This is not the only member of the family Lamiaceae to be called Pennyroyal, several other genera have this common name. In Culpeppers Herbal the pennyroyal he refers to grows in damp areas and flowers at the end of August.

Spring flowers III- Color wheel cycle

bluebonnet

There is something joyous about a field of flowers.  When nature repeats with reliability, like the appearance of the bluebonnets, it penetrates through the layers of our lives that separate us from our natural surroundings.  Not only do we reconnect to seasons through plants, but it also serves as a subtle measure of the health of the ecosystem.  Note all the news reports on wildflower predictions each year.

indian paintbrush

What is perhaps just as remarkable, but less remarked on, is the subsequent unfolding of flowers, annuals and biennials, through the spring.  The Bluebonnets (Lupinus texensis) are among the first to appear with the occasional patch of Indian paintbrush (Castilleja coccinea) to highlight the colors tastefully.

bluebonnets and indian paintbrushes

scrambled eggs growing in a naive lawn

What follows is the sequential flowering of different species.  Many from the Asteraceae and while some, like scrambled eggs (Corydalis curvisiliqua) are from more obscure families like Fumariaceae.  Together they form layers in the landscape in space and time.  The casual manner in which the form and color of these species, frequently seen on roadsides, complement each other always strikes me  as rather amusing given the effort and time someone might put in to create the same, very temporary effect.  Eventually the fields of blooms give way to smaller and smaller patches until finally we arrive at the enormous sunflowers of the summer.

brown eyed susans (all yellow) together with firewheels (orange and yellos)

The ever changing mosaic of these roadside species is largely connected to environmental conditions and germination requirements.  Some seeds, like those of the bluebonnets require stratification and fall rains for the plants to germinate and begin growing well before Christmas.  Similarly, the firewheel (Gaillardia pulchella) seen here with brown eyed susans (Rudbeckia hirta) should be planted early as they require 70F to germinate and so may only appear the following spring if the weather warms up too quickly.

Missouri primrose (Oenothera macrocarpa

pink evening primrose (Oenothera speciosa)

While the annuals and biennials are tied to seasons through seed germination.  It is possible that perennials might offer more reliable color, although their flowering (timing and profuseness) is tied to weather conditions as well.

Primrose is a common name applied to members of the genus Calylophys sp.  and Oenothera sp, both found in the Onagraceae.  These species provide alternate yellows to the early daisies and occasionally delicate pink.

wine cup

The purple/blue range of the spectrum can be found in the wine cup (Callirhoe digitata).  A perennial with a deep tap-root, it has leaves close to the ground year round, but sends dramatic purple flowers up over grasses and neighbouring plants early in the spring.  A more upright form is that of Widow’s tears (Commelina erecta) which, while

Widow’s tears

low (growing about 1-3 ft tall), offers a vertical line in contrast to the Purple prairie verbena (Glandularia bipinnatifida) that grows profusely with a relaxed habit that is frequently covered with butterflies.

Purple Prairie verbena

cedar sage

Hummingbirds find a food source in the bright red cedar sage (Salvia roemeriana). With it’s attractive leaf it brightens shady spots from early spring until mid summer, providing dramatic contrast to the white caliche stone and brown mulch found in forested areas.

Spring in Texas clearly offers a diverse palette of color and form.  To mimic the natural sequence and arrangement of wildflowers one must understand both germination and flowering requirements of the plants selected.  Like a puppet master it is all in the timing of seed application, watering and of course placing of both perennials and the annuals/biennials.  Can you imagine selecting 4 or 5 species to place in an area for a spring show?  Can you imagine a “meadow” effect in say a 3×3 ft area?  What are the important criteria that we can take from nature to implement in design in order to attain that effortless look of sequential color?

Contrasts in Texture

Image

We might be very familiar with the red poppy (Papaver rhoeas), a European native Imagecommon in disturbed areas, or even the yellow Californian poppy (Escholzia californica), native to the USA.  But we might not be so quick to recognize the prickly body of the White Prickly poppy (Argemone albiflora).Image  This Texas native is a survivor, preferring to grow in disturbed and nutrient poor conditions.  It can be seen on the roadside in many southern states and has a rose-pink variant in Southern Texas.  An annual or biennial, it has delicate paper white flowers beloved by bees and butterflies but shunned by deer and cows.  Probably because it is very prickly and toxic.  It produces copius quantities of seeds and would possibly be a good candidate for restoration in very disturbed sites where people would not necessarily pass to close by.  Given it’s deep root system I wonder if it would also be a candidate for phytoremediation?

Things are never quite what they seem

Nothing should be taken for granted.  Out at the Bamberger Ranch last in February we were treated to early wildflowers.  Over the past three years I have been out to this private ranch at the same time and we seldom have any flowers to look at.  This year, a mild winter and regular spring rains have filled rivers and encouraged early flowering of several different species.  Colleen Gardner, executive director, told us that from September 2010 to September 2011 they had had approximately 4 in of rain.  Since then they have had approximately 6 in and it is still coming!

And so the flowers bloom.  One in particular caught my eye – Puccoon or Lithospermum incisum.  This perennial is found in the majority of the states in disturbed and open areas near woodland.  In some states it is endangered or even eradicated!  The plant pictured here was on the side of a path at the base of a steep limestone hill.  It appears that plants that are found from Kansas south are typically smaller than those found to the North (Govoni 1975).  Flower form and vegetative characteristics vary greatly, independent of one another and depending on environmental characteristics.  Generally wetter conditions produce bigger plants.  The flowers are not always obvious as they are sometimes hidden by leaves.

The very beautiful but relatively scentless flowers can be seen from March to May in Texas and into July in other states.  Surprisingly these pretty flowers are mostly sterile!  Later in Spring and Summer puccoon plants will produce hidden flowers that will self-fertilize without opening.  This type of flower is said to be cleistogamous.  This condition is not as rare as you might think.  The genus Viola sp.  and many grasses utilize this reproductive mode.  Some species are known to use it in response to damage or environmental stress.  The opposite of cleistogamous is chasmogamous which describes flowers that open before fertilization and are usually cross pollinated.  Interestingly annuals are frequently cleistogamous (or self-pollinating) and perennials are cross-pollinated.  Whatever the breeding system is the literature suggests that annuals are more succesful than perennials at setting viable seed (85% in annuals and 50% in perennials – Wiens 1984).  So I am left with three questions:  Firstly why does Pucoon bother to have such beautiful flowers? Secondly, what is the genetic make up of this curious species and Is there a way to grow this flower horticulturally so that it could take the place of Pansies or other spring bedding plants?

References

Harris and Harris.  2001.  Plant Identification terminology

Enquist.  1987.  Wildflowers of the Texas Hill Country

Wiens.  1984.  Ovule survivorship, brood size, life history, breeding systems,and reproductive  success in plants.  Oecologia. Volume 64, Number 1, 47-53

Govoni.  1975. Evidence for Divergence in Lithospermum incisum Lehm. in the Western Great Plains.

Taxon   Vol. 24, No. 4.  431-441