GENETICS AND EVOLUTION

 

Evolution is commonly seen as a complex aggregation of random genetic mutations.

 

A gene with location of probable mutations – alleles

 

Convergent evolution would suggest, instead, that similar environmental pressures generate similar solutions. In other words – similar environments select for the same characteristics or traits.

One of the most fundamental lines of evidence comes from the study of comparative plant morphology. Although there are MANY exceptions – it seems nature reuses the same solutions – over and over again. Understanding which characteristics and structures belong to each type is an important part of understanding plant morphology.

 

White hairs on Dusty Miller – says sunny and windy

 

For example, the fronds of Bryopsis plumosa and stems of Asparagus setaceus both have the same feathery branching appearance, even though one is an alga and one is a flowering plant.

 

Bryopsis plumose – an algae

 

Asparagus setaceus – a flowering plant

 

If you look at the growth form of many cacti and species of Euphorbia – you will see they are very similar, even though they belong to widely distant families. The similarity results from common solutions to the problem of surviving in a hot, dry environment. IE: Water collecting stems, stems covered in wax, few to no leaves, thorns and spines for protection, roots that spread outwards in all directions, and column shape stems.

 

Cactus – thorns, thick stems, no leaves

 

Euphorbea – similar to cactus !

 

As follows is a list of morphological traits and the environment in which they evolved. By comparing traits on a new plant we never worked with before – one could deduce which environment it came from. Thus, make a better decision on WHERE to use it in a garden. It is also helpful identifying which plants can come together in one planter by comparing their watering or lighting needs.

At Plant Specialists – Our Design and Garden Care Teams both use this tool all the time !

A word of caution: DO NOT rely on only one characteristics to match a plant to an environment. Several matching characteristics are NECESSARY. This is because nature uses the same solutions to different environments.

For example, a hairy leaf could indicate its either Alpine (cold), Mediterranean (windy), or rainforest floor (water deflection). To distinguish between them you then have to look at other characteristics as well.

 

Creeping thyme – small leaves with tufted hairs protect from cold and wind

 

Lavender – small waxy leaves with white hairs protect from high sun and wind

 

African violet – pivoting leaves with parallel hairs protect leaf surface from water droplets

 

MORPHOLOGICAL TOOL

 

Bark – thick (the thick outer bark protects the cambium layer)

Adaptation to extreme cold –  Pinus genus – use in a location with a lot of cold exposure

Adaptation to heat –  Juniper –  can be use near an AC vent

 

Bark – thin (the thinness allows for less use of resources)

Adaptation to a cool and humid forest – Malus (apple and crab apple) – use in a protected location

 

Bud – covered (the hard covering protects the bud from damage)

Adaptation to protection from physical abrasion or winter dehydration – Magnolia stellata – use in a windy spot or has people traffic

 

Bud – sugar covered (the sugar keeps bud from drying out)

Adaptation to protection from spring dehydration – Apple – use in a secluded spot

 

Flower – ligule ( the ligule protects the new growth from wind abrasion) – Grasses  – use in a windy spot !

 

Leaf – blueish (Blue is a pigment used in photosynthesis and in shade you need more)

Adaptation to lower light – Hosta and Begonia – use in partial shade

Caution: Some Agave and full sun plants like Juniper look bluish also – this is from the surface wax on their leaves – an adaptation to dry hot and sunny environments – if wiped off – underneath its greener !

 

Leaf – dark green (It needs more green chlorophyll to compensate for lower light)

Adaptation to Heavy Shade – Mahonia – use in deep shade

 

Leaf – olive green (right as rain! – good mix of yellow and blue pigments)

Adaptation to a Full Sun Sunny spot – Example: many plants !

 

Leaf – reddish (red is a pigment used in photosynthesis that leaves use to protect themselves from solar rays – a sun block !)

Adaptation in new leaves – new growth in Rose (sunblock) and Pieris – use in a sunny  spot

 

Leaf – pink (red is a pigment used in photosynthesis that leaves use to protect themselves from solar rays – a sun block !)

Adaptation to sunny environment – Pink Beech and polka dot plant – use in Full Sun only

 

Leaf – purple (A blue/red pigment – called anthocyanins that changes with pH used to block solar rays – another sunblock! )

Adaptation to sunny environment – Purple leaf maple and sweet potato vine – use in Full Sun only

 

Leaf – red (red is a pigment used in photosynthesis that leaves use to protect themselves from solar rays – a sun block !)

Adaptation to sunny environment – Red maple – use in Full Sun only

 

Leaf – pointed tip (the tip channels the rain drops off the leaf)

Adaptation to a rainy environment – Birch – water it constantly!

 

Leaf – small, green (small leaves do not need to be big to capture all the solar energy they need)

Adaptation to a sunny environment – Boxwood – use in Full Sun only

 

Leaf – large, green (Large leaves need to be big to capture all solar energy they need)

Adaptation to shady environment – Hosta – use in shade

 

Leaf – hairy (Hairy leaves slow down transpiration)

Adaptation to wind – Generally – use in a windy spot

 

Leaf – hairy and tufted (tufted hairs protect the center growing area from freezing)

Adaptation to an Alpine environment – Creeping Thyme – use in a exposed spot

 

Leaf – hairy and white (white hairs reflects sun)

Adaptation to a sunny and windy spot – Lavender and Chamomile – use in Full Sun only

 

Leaf – hairy and tightly packed / parallel (hairs channel the rain to run off the tip)

Adaptation to a rainforest floor –  African violet – use in shade

 

Leaf – variegated (cells with no pigment do not photosynthesize and needs to be in sun)

Adaptation to Strong Sun – Variegated Iris – use in Full Sun only

 

Leaf – thick wax (The wax does not allow fungal spores to touch the leaf tissue)

Adaptation to a rainy environment – Camellia – use in protected spot

 

Leaf – white wax (The white reflects the sun, the wax stops dehydration)

Adaptation to a hot and sunny environment – Juniper – use in Full Sun only

 

 

Our Landscape Design Team uses these criteria when selecting plants for the long term survivability of your garden.

Call us – let’s talk leaves !

 

PLANT SPECIALISTS
GREENING NEW YORK FOR OVER 53 YEARS !

 

 

 

Article written by our Staff Horticulturist, Peter B Morris, BSc, MSc, MBA

All photographs used with permission @SHUTTERSTOCK