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.

burroak2

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.

spanishoak2

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.

flameleafsumac

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Flora vacations #1

Looking down into Cape Town from the top of Table Mountain, Lions head off to the left

Since it’s the time of year to get together with family, I thought I would post a “holiday”post about the flora of my home town – Cape Town.  The Cape Floristic region is world-renowned for its unique and fascinating flora.

Pincushion (Leucospermum conocarpodendron) framing the walk up to the mountain

Pincushion (Leucospermum conocarpodendron) framing the walk up to the mountain

Elegia capensis – Restionaceae

A Mediterranean ecosystem that is frequently compared to that of California, Australia and, of course the Mediterranean, it has its own set of unique species that are adapted to its acid soils and winter rainfall.  It is indeed so special, with 8200 species in an area 1/3 the size of Britain, that in 2004 it was declared a World Heritage Site.  One of the gems in the crown is Kirstenbosch gardens.  Situated on the back slopes of Table Mountain this garden displays many of the unique and beautiful species found in Fynbos and in other flora of South Africa.  Many of these species are popular, not only locally, but around the world and have been developed for horticulture.  As a site with multiple uses, providing access to mountain walks, acting as a music and art venue, Kirstenbosch is popular with locals and tourists alike.When walking on Table Mountain there are many extraordinary plants to see.  Families that are common in Fynbos and relatively rare globally are Proteaceae,

Mimetes hirtus

Helichrysum vestitum (Asteraceae)

and Restionaceae.  Unique genera of the Proteaceae, such as Grevillea sp., are also found in Australia.

Ubiquitous families like the daisies (Asteraceae) are well represented too.  Pictured here is an example of the group known as “Everlastings”, the ray florets of this group have a papery texture and dry very well making them popular with florists.

Disa uniflora

Herschelia graminifolia – blue disa

Even the more delicate gems of the plant world can be found here.  It is quite possible that climbing on the mountain in summer or winter you might come across members of the family Orchidaceae.    Many of the species such as Disa uniflora are well-known by enthusiasts around the world and bred with great care.

Everlastings and Leucodendron sp. on the mountains of the Cape Peninsula

The diversity of species and form is connected to the dynamic patchwork of soil, water and light conditions that are found in the mountains and plains of the region.   Trees of the temperate forests line the Kloofs, while grasses and shrubs vie for space on sandy flats, and a successional array of bulbs, forbs and shrubs are to be found all over the micro climates of the mountains.

Evidence of fire on the Cape Peninsula mountains

But all the species that are found in this dynamic landscape have to be able to cope with fire. Fire is a transformative element in the landscape patchwork and plants are able to survive by employing different strategies.  Some plants produce myriads of seeds holding them in protective structures until the fire has passed.  The fire stimulates the release of seed of these serotinous individuals and the smoke of the fire stimulates seed germination.  Another strategy is to protect the meristematic buds beneath the surface of the soil and resprout after fire., taking advantage of a nutrient rich environment with few competitors.

It is interesting that many of the remarkable species of this landscape have been developed for horticulture and utilized around the world in gardens.  In agriculture species, such as corn or the apple, have not appeared desirable at first and have been worked for centuries to obtain the suite of appealing characters that we now enjoy.  It makes me wonder what inconspicuous species lie in wait in the many different flora around the world, waiting for some creative enthusiast to spot their inherent beauty and potential.

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?

Considering Native Plants

When considering plants in a landscape there is often an emphasis on using local or native species.  Ignoring the all important “What constitutes a native species?” .  The next consideration is “Why use native plants?”.  This is hardly a new question in the world of landscape design.  But there is a persistent myth that using native plants in landscape makes things easier and less costly.  That statement invites an interesting debate which points to the fundamental requirement for knowledge about plants and their interaction with the environment.   Planting anything without insight into the basic biology and ecology of a plant is playing “landscape roulette”.  It is also necessary to have both macro- and micro- understanding of an area

Hawaii Savannah on Lava

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Texas Savannah on Limestone

Fortunately this is relatively easy to achieve given the growing body of knowledge of plant eco-physiology and the fact that ecological patterns appear like repeating fractals at different scales.

Take for instance the standard world biomes map we see patterns connected to climate and vegetation.  It is not surprising that if we look at a map of the Texas “ Natural Regions” or “Ecoregions” we see similar patterns of vegetation connected to topography, rainfall and temperature.

Thus, learning to “read” the landscape is as important as getting to know the foibles of the local “characters” – the plants.  And we still need to answer why “locals” should get preference.

In nature where a plant is seen to grow is the result of a history of seed dispersal, germination conditions and physiology.

Fire senescent Protea sp. in South Africa

In a constructed landscape where a plant grows is the result of someone’s intent and care – and the physiology and biology of the plant.

Mammilaria cactus, Texas

Knowledge and experience of the plants, climate, ecology and landscape purpose are fundamental to success in a situation that is largely bound by the laws of nature.

So what is important in considering conditions for creating landscape are those same things that define broader picture of natural plant dispersal – rainfall and temperature, topography and soil.  [Useful documents like the soil types of Texas, describe in great detail local conditions – to the point of being overwhelming].  But these environmental variables are usually far from static, or predictable, and it is not necessarily the averages which define a plant’s distribution.  More often it is the extremes.

Consider the climate in Austin.  If you view the averages it appears to be a pleasantly warm climate, view the extremes and it is possible that a plant has to deal with freezing temperatures and days of 100+F in the same year, not to mention winds, excessive rain or no rain at all.

We are all very aware of the growing challenges associated with rainfall. Last year presented Texas with its worst drought in many years (US total precipitation 2011), and there does appear to be a shift in rainfall totals over the past decades (changing US rainfall since 1960).

It is not only rainfall that is shifting.  The USDA has recently published a new plant hardiness map minimum temperatures that reflects changes in climate.  There is finally recognition that the hottest temperatures challenge plants as well and the American Horticultural Society has produced a heat zone map.

Perhaps the most hidden, or least considered factor, is how land is actually being used.  A new vision that considers human land use in an ecological context makes the world biomes map we are familiar with seem grossly oversimplified.  Anthropogenic biomes and the impact of human land use at a local level highlight the importance of intelligent and ecologically informed decisions with regard to landscape, particularly in the urban setting.  This picture of the less than pristine biome, ever-changing land use, and pressure on fundamental natural resources, such as water, should lead us to expand the role of plants in the intelligently constructed landscape.  Plants are the ecological go-between,  the mediator between static urban structure and capricious natural events and forces.

Now having considered our landscape, we can return to the questions “why use native species?” and “what constitutes a native species?”.  Situated in context of the immediate environment the conversation may be less academic.

Ephemeral art

Cooperia pendunculata (Amaryllidaceae)

Rain in Central Texas is a remarkable event.  For the past few years we have waited for rain so long that even a sprinkle is a reason to rejoice.  Alternatively there is a downpour of such intensity that you can only stand and marvel.  Different plants deal with the dichotomy of dearth and plenty in different ways.  Some like, trees and shrubs put down deep and extensive roots to wait out the hot, dry spells.  Annuals gamble all on appearing early and letting the next generation wait for pleasant conditions inside a seed.  The rain-lily has the amazing ability to time flowering immediately after rain events, seeming to pop up anytime of year.  In reality there are two species, C. pendunculata which tends to flower in the spring and early summer, and C. drummondii whose slightly smaller flowers rise up after late summer and fall downpours.

The yellow center of the rain lily. The three inner tepals are visible, backed by the outer tepals (two of which can be seen)

After rain a green stem grows up from a subterranean bulb.  Rising between strap like leaves the pinkish colored bud opens revealing a short-lived luminescent white flower.  The center of the flower is yellow but the bud and outer tepals have a faint pink hue increasing in intensity towards the central vein of the tepal.  These fragrant flowers seem to glow briefly, often in the brown grass of a parched landscape.

A field of rain lilies is a spectacular sight for almost a week in some cases, especially if there are sequential rain events.  Once one appears in a landscape they seem to seed and spread relatively quickly and easily, especially given consistent moisture.  I love to imagine growing the bulbs beneath the sides of a gravel walk, or in spaces amongst cacti.  They are wonderful reminders of the blessings of rain and regeneration, similar to that which we enjoy in the spring.

Rain lilies growing under a live oak. They are on the side of a paved driveway and receive no supplemental water.

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