Texas Mountain Laurel – Sophora secundiflora

OLYMPUS DIGITAL CAMERASpring is springing up quickly after our warmish winter.  The mountain laurels have been blooming for over a month now and are slowly beginning to fade.  Their bumpy seed pods, containing poisonous seeds, are appearing from the delicate purple-blue blooms that still fill the night with heady scent.  I thought it might be fun to take a closer look at these flowers since this species is a member of the Fabaceae, one of the largest and most cosmopolitan of all plant groups. Just about anywhere in the world you will find examples of the pea family.  They could be evergreen, deciduous, climbers, herbaceous plants or trees.  Specifically, Texas Mountain Laurel is a beautiful evergreen multi-trunked trees that is part of the sub-family Faboideae.  This is the group of Fabaceae that we typically recognize as “pea”. OLYMPUS DIGITAL CAMERA The other two subfamilies are Mimosoidae and Caesalpiniodae.

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Half flower diagram of Texas Mountain Laurel

So what is a “classic” pea flower. It has a floral structure where the petals are arranged into banner, wings and keel.

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Stigma, style and ovary of the Texas mountain laurel

The banner is one large petal with two wing petals enclosing two keel petals.  The keel closes around the 10 stamens  and the ovary that will later develop into the pod if the flower is pollinated.  Two curious features of the flower are the widening of the filaments at the base (filaments support the anther forming the stamen) and a protrusion on the lower side of the keel petal which seem to help the petals stay closed over the stamens and stigma.

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10 stamens clustered tightly around the gynoecium

Fall Color

cedar elm (Ulmus crassifolia)

cedar elm (Ulmus crassifolia)

While many parts of the country have begun their winter, here in Texas we are still enjoying the balmy days of Autumn.  While our fall color isn’t perhaps as dramatic as some places in the country we still have some lovely yellows and reds set against the backdrop of the evergreen cedar. (Juniperus ashei).  Cedar elms are tall stately trees that can be found on their own or hidden within the forest.  This year their small winged fruits covered the ground in September and October as their yellow golden leaves are doing now.

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Bur oak (Quercus macrocarpa)

Another source for hints of gold on the hillside is the Bur Oak.  The leaves of this oak are enormous as are their beautiful acorns that have caps with dramatic “burrs” surrounding them.  A beautiful tree in a park setting this wonderful tree is now dropping its leaves, that are the size of a childs shoe, making a crunchy brown flooring for park goers to enjoy in the fall light.

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Spanish Oak (Quercus buckleyi or texana)

Oaks are also a source of dramatic reds seen along roads and on hillsides. The Spanish Oak belongs to the group of Oaks known as the Red Oaks and doesn’t disappoint. The identification of this fast growing species can be tricky as it has much in common with the Shumard Oak (Quercus shumardii) and Southern Red Oak (Quercus falcata). Another source of deep red is from a slightly small tree, the flame leaf sumac (Rhus lanceolata). This wonderful plant specimen changes from a vibrant green in the spring to a deep red in the fall. It candelabra like inflorescences of tiny cream flowers resulting in reddish seeds which marks the beginning of the change in late September/October. Their color emphasized by the late fall light they optimize winter metaphor of burning the old and opening ways for new beginnings.

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Flowering phases II: Spring flowering Shrubs

Yellow blooms of Agarita seen in February

Like trees, shrubs are appealing not only for their attractive flowers, but also for their permanence in the landscape and the possible offering of food in the fall.  Thus, while it is interesting to note those early bloomers, that help to wake up the landscape and our senses, paying attention to leaf shape and architecture can add a subtle dimension to landscape.   Walking around the back paths of the LBJ Wildflower center early one spring I smelt the most delightful sweet scent.  It was particularly elusive but, following my nose for a bit, I was able to trace it to the Agarita bushes.  It surprised me that such a delicate smell game from the strings of small yellow blooms  as the bush itself is incredibly robust and the leaves are uncomfortably prickly, just like a holly’s.  In fact it is known to be selected by birds for nest sites as the dense prickly foliage offers excellent protection.  As the picture indicates the ephemeral yellow blossoms result in bright red berries later in the year.

Flowers of Texas Persimmon

Diospyros texana is a wiry looking shrub.  It offers a great sculptural element to the landscape heightened by its beautiful bark.  In the spring it has delicate little bell-shaped flowers that produce fruit later in the summer.  The small fleshy fruits of this hardy tree provide food for birds and small mammals.

Fading blooms of Eve’s Necklace

Seed pods of Eve’s necklace

In the woodland, surprisingly tropical looking blooms hang overhead.  Eve’s necklace (Styphnolobium affine) offers graceful stems, delicate pink yellow blooms clustered on dangling infloresences and vibrant green compound leaves that move easily in the breeze.  While it is a very attractive, it should be notes that the black seed pods house toxic seeds.  Similarly it’s close cousin the evergreen Texas Mountain Laurel (Sophora secundiflora) has very attractive blooms that have a sweet scent, particularly evident in the evening, that give rise to silvery seed pods housing toxic red seeds.  This is a very popular landscape tree, although it is slow growing, and this year the flowering in February and March was remarkable!  This may be connected in some way with the drought/spring rain weather patterns that we experienced.Part of the delight of a Texas spring is the advent of the rains and the filling of the creeks.  Here along Bear creek, a contributor to the Edwards aquifer, we find Button bush (Cephalanthus occidentalis).  This versatile shrub is particularly useful in riverine areas.  It does not mind having it’s roots regularly or partially submerged and it offers both nectar to insects and seeds to ducks and rodents.  The glossy green leaves present a third leaf type to consider, the entire leaf.

Our introduction to these species presents us with further considerations for the landscape.  We had already met the idea of host plants (with Agarita and Texas persimmon), but now we introduce the possibilities of evoking interaction through the senses, smell and sight.  Scents can be intriguing and invite exploration while different leaf shapes offer visual interest.  Can you suggest particular arrangements or collections of shrubs?  How do they meet with your selection criteria?

The diversity of the ‘star’ flowers – Asteraceae

Black foot daisy (Melapodium leucanthum) – Tribe Heliantheae

Firewheel (Gaillardia pulchella) – Tribe Helenieae

A humble daisy is the characteristic member of this cosmopolitan group.  You can imagine that a plant family with members spread across the globe might well have species occupying a range of niches.  The vast diversity is taxonomically captured by dividing the family up into sub families and tribes.

The tribes that you might be the most familiar with are the Heliantheae and Helenieae (the classic daisy form), the Cynareae (artichokes and thistles)

Texas thistle (Cirsium texanum)

, Astereae (which has Golden rod and the fleabanes as members)

Prairie fleabane (Erigeron modestus) – Tribe Asteraeae

and the ubiquitous Chicorieae (dandelions and chicory).

Colorado dandelion

While most asters (or composites) are herbaceous perennial, biennials or annuals there are also shrubs and vines.  The complexity of this group extends to its taxonomy and you may see frequent name changes.  In fact you might see the family referred to as Compositae!  This name is in reference to the classic head inflorescence of the family.The flowers (disc florets) are typically collected together and surrounded by what are termed ray florets.  You might be tempted to call them petals but they are in fact a different type of flower to the others on the head.  In the image to the left you can see (from outside to center)the large yellow ray florets, the  yellow stigmas (female parts) of individual flowers and the brown anthers (male parts) in the center disc florets.

The curiously square bracts of Nerve- ray (Tetragonotheca texana – Tribe Heliantheae)

Below the inflorescence are bracts that you might mistake for sepals (if you viewed the whole daisy as a flower).  The bracts of different species are quite different and might even be sticky or spiky!

Brownish bracts of Navajo tea ( Thelesperma simplicifolium – Tribe Heliantheae)

Helianthus maximiliani

Ratibida columnaris

Here we have a classic example in the case of the sunflower – Maximilian sunflower to be exact (Helianthus maximiliani – Tribe Heliantheae).  A variation on this capitulum inflorescence is Ratibida columnifera (also in tribe Heliantheae) where the platform of tiny flowers are proud of the bronze or yellow ray florets.

The multiple inflorescences of Poverty weed

Of course Nature never obeys our taxonomic rules so there are other members of the family that do not have the classic daisy flower.  Poverty weed (Baccharis neglecta – Tribe Astereae), for instance, does not conform to the usual idea of a “daisy”.  A tall shrub, it grows well in disturbed areas and is very difficult to remove!  In fall it becomes very attractive covered with multiple inflorescences.  It’s overall silvery appearance earns it a place in the landscape.  Come spring I will be wondering how to get rid of it again!

Blue mist flower (Eupatorium coelestinum – Tribe Eupatorieae)

You can see that the inflorescence of poverty weed lacks the ray florets common in other tribes.

They are also much reduced or absent in the Eupatorieae.  Blue mist flower (seen here with friend) (Eupatorium coelestinum) is a beautiful summer flowering example of this tribe.  There is a wealth of hardy Asteraceae species that can be utilized for different effects in the landscape.  They are a global family well worth exploring.

Hidden Jewels

The delicacy of Texas plants frequently surprises me.  One of my personal favorites that I look for each spring is the Pearl milkweed vine, or netted milkweed vine (Matelea reticulata) that is endemic to Texas.

Seen here with the White leaf leather flower (Clematis glaucophylla), this small green flower with brown-red speckles has a center that is pearl colored.  What is even more surprising is the comparitively enormous pod that appears.  This type of seed pod is not uncommon in the family that this vine belongs to -Asclepidaceae.

This vine that twines 15-20 ft up trees and over shrubs is not very obvious until the eye-catching spots of silver appear.  It is interesting to imagine it as one of several over an arch or along a fence.  Where could you imagine using it?

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