#30 - Aug 2019 - Garden Stuff - © Sandy Lang - slang@xtra.co.nz
STRUCTURE & COMPETITION
July/August: Late winter. Temperatures rising. Prune soon, else early-swelling buds are easily knocked off. Prune in dry weather (disease enters wet pruning wounds). Seal larger wounds with house paint…
Time to buy new trees/shrubs. Choose the best plants. Buy early to get first dibs on what’s available. Buy late and you get others' rejects. Plant in August/September.
Plant origins: Plant life started as individual unicells in seas/lakes. Later, these learned to stick together to form colonies. Sometimes they got washed ashore.
•Most dried and died but some learned to exude slime to slow down drying. About 450 million years ago, the first simple land plants appeared – biofilms – green unicells stuck to damp rocks with exuded slime. Biofilms are still around, on our roofs, paths, fences (Google Pleurococcus). •Later, some cells in a colony became specialised and so these colonies became the first, simple, multicellular plants.
Cell structure: A typical plant cell is surrounded by a super-thin membrane (very fragile but very smart, as it contains and controls the mix of soluble contents). •Outside this is a fibrous cellulose cell wall (very tough and leathery - but very strong in tension). •Outside this is a thin, waxy cuticle (very waterproof). •Cells are pumped up full of water (osmosis), their internal turgor pressure 10-times the pressure in a car tyre. Cell firmness depends on cell turgor. For cells, think tiny footballs; for wilting cells, think tiny footballs needing pumped up.
Tissue structures: Most plants are multi-cell structures made of facetted cells (think bricks) glued together with pectins (think mortar). •Small, thick-walled cells are stronger than big, thin-walled ones. So, plants use small cells for the skin and fill up their inside spaces with big cells and air. •This turgid, multicell structure is strong enough to build a leafy herbaceous plant up to about 1 m tall. That’s big enough to overshadow a green slime and steal away its sunlight (energy).
BIG structures: Impregnate a cellulose cell wall with lignin (like epoxy resin) and its texture becomes harder, less leathery, still very tough (think fibreglass). •Elongate the cell, thicken its wall and let it die and, bingo, a fibre-reinforced resin wood cell. •Woody plants are to non-woody plants, as steel-reinforced concrete buildings are to brick ones - lets you build skyscrapers. •Forest trees grow up to about 100 m tall and steal the sunlight (energy) from herbaceous plants. •No wonder our world was mostly forest - till we came along and messed it all up…! ___________________________________
STRUCTURE & COMPETITION
July/August: Late winter. Temperatures rising. Prune soon, else early-swelling buds are easily knocked off. Prune in dry weather (disease enters wet pruning wounds). Seal larger wounds with house paint…
Time to buy new trees/shrubs. Choose the best plants. Buy early to get first dibs on what’s available. Buy late and you get others' rejects. Plant in August/September.
Plant origins: Plant life started as individual unicells in seas/lakes. Later, these learned to stick together to form colonies. Sometimes they got washed ashore.
•Most dried and died but some learned to exude slime to slow down drying. About 450 million years ago, the first simple land plants appeared – biofilms – green unicells stuck to damp rocks with exuded slime. Biofilms are still around, on our roofs, paths, fences (Google Pleurococcus). •Later, some cells in a colony became specialised and so these colonies became the first, simple, multicellular plants.
Cell structure: A typical plant cell is surrounded by a super-thin membrane (very fragile but very smart, as it contains and controls the mix of soluble contents). •Outside this is a fibrous cellulose cell wall (very tough and leathery - but very strong in tension). •Outside this is a thin, waxy cuticle (very waterproof). •Cells are pumped up full of water (osmosis), their internal turgor pressure 10-times the pressure in a car tyre. Cell firmness depends on cell turgor. For cells, think tiny footballs; for wilting cells, think tiny footballs needing pumped up.
Tissue structures: Most plants are multi-cell structures made of facetted cells (think bricks) glued together with pectins (think mortar). •Small, thick-walled cells are stronger than big, thin-walled ones. So, plants use small cells for the skin and fill up their inside spaces with big cells and air. •This turgid, multicell structure is strong enough to build a leafy herbaceous plant up to about 1 m tall. That’s big enough to overshadow a green slime and steal away its sunlight (energy).
BIG structures: Impregnate a cellulose cell wall with lignin (like epoxy resin) and its texture becomes harder, less leathery, still very tough (think fibreglass). •Elongate the cell, thicken its wall and let it die and, bingo, a fibre-reinforced resin wood cell. •Woody plants are to non-woody plants, as steel-reinforced concrete buildings are to brick ones - lets you build skyscrapers. •Forest trees grow up to about 100 m tall and steal the sunlight (energy) from herbaceous plants. •No wonder our world was mostly forest - till we came along and messed it all up…! ___________________________________