Euphorbia heptagona keeping its distance

Personal space is a need of living entities. Individual differences may exist in many or most species as to how much is required or sufficient. People vary individually in how much space they need. They also vary in this need over time: during normal life activities (like eating, sleeping, defecating or mating), during different moods, life stages and who the other party or parties might be that should come hither or move yonder.

Plants grow well and perform well in flower and seed production when they have sufficient space. What that space might be varies for a given species as can be seen on seed packet instructions as to how far apart seedlings should be planted for maximum effect. This will also vary according to soil type, the lie of the land and climatic conditions.

Euphorbia heptagona and its neighbours appear a little standoffish on their Little Karoo shale slope in this photo. If rainwater arrives slowly, it tends to sink among the stony layers and surface roughness gaps, captured to an adequate degree for moisture needs until the next rain. Most of these perennials invest in deep root or taproot growth, to be ready to receive wherever the water sinks too. All goes better if the roots of neighbours are over there, nowhere too close!

Annual plants among them capitalise on their seeds being captured at the end of a windy flight under some of these plants. Their shorter roots will still do the job because they flourish and complete their life cycles quickly after rain, supported in the shady areas where moisture retention is better. Many annuals survive their off-seasons in dry seed form, their plant bodies incapable of living through the temperature or moisture challenges of some seasons endured by their habitat. 

Slightly bigger stands and wider streets keep the peace, community relations and quality of life better. Smaller stands enrich developers and municipalities. The naturally gregarious versus peace and quiet, hooligan crowd or misanthrope loner do their thing according to natural tendencies and disappear or adapt as power sorts population density out.

Like people, plants also have to cope with varying population density that results from breeding habits and environmental conditions. If the newly formed top soil and humus resulting from vegetation detritus aren’t removed by rain and wind, more seeds will germinate here, eventually leaving less space. All residents compete for sun and supplies, sometimes succumbing to the robust growth of bigger players.