Why a pencil still beats a photograph

A photograph of a marsh marigold records a plant at one moment; a sketch records what you noticed. The difference matters most in wetlands, where the plants you have travelled to see are often wedged between tussocks, half-submerged, or leaning into the wind. A camera will capture the tangle. A pencil will make you untangle it.

Drawing forces the eye to answer questions a photograph lets you postpone. Does the leaf stalk join the stem opposite another, or does it alternate? Is the stem round or triangular? Are those hairs on the leaf edge, or only on the veins beneath? By the time you have drawn the answer, you have learned it. Ten minutes of sketching on a boardwalk will teach you more about water mint than an hour of photography.

There is a second reason, more melancholy. Colour fades. A picked purple loosestrife spike will have dulled by teatime; bogbean petals curl within minutes. Draw the structure first, then note the colour in words. The plant will last on the page long after it has gone over.

The kit that fits in a coat pocket

Field sketching fails when the kit is too heavy or too precious. Keep it small and cheap enough that you will actually carry it.

• Notebook: A5 or smaller, hard-backed, with plain or faintly ruled pages. Waterproof paper earns its cost in a reedbed; ordinary cartridge paper is fine if you keep it inside a coat.
• Pencils: one HB and one 2B, plus a small sharpener. Pencil works on slightly damp paper and does not bleed when it rains; ink does both badly.
• Hand lens: a folding 10x lens on a cord around your neck. Keep it there and you will use it; in a pocket, you will not.
• A bulldog clip to hold the pages flat in a breeze, and a short ruler or marked pencil so every sketch carries a scale.
• Wellies and a sit mat. Not glamorous, but sketching is stationary work, and cold feet end sessions early.

Draw the habitat before you draw the plant

Spend two minutes on the setting first. A few quick marks will do: the waterline, the slope of the bank, the tussocks, the direction the channel runs. Note the associates growing within arm's reach — the plants a species chooses to grow beside tell you as much as the species itself. Yellow flag iris standing in shallow water, water forget-me-not at the muddy margin, common reed behind.

Write down what your feet are doing. Are you standing on floating vegetation, on peat, on silt? Is the water still or moving? These notes are the difference between a drawing and a botanical record.

Leaves, stems and the details colour hides

Leaf arrangement is the first thing to settle. Look at the stem: are the leaves paired at each node, alternating up the stem, or arranged in whorls of three or more? Number the nodes on your sketch. It sounds pedantic until the third time you have tried to identify a plant from a photograph that does not show it.

Next, cut a stem and draw the cross-section at real size, then at twice size. Is it hollow, solid, ridged, winged? Grasses, sedges and rushes sort themselves out here: sedges have edges, rushes are round, grasses have joints. It is a rough rhyme, but it carries you a long way on a wet afternoon.

Then bring out the hand lens and draw one detail large — five or ten times life size. A ligule where the leaf blade meets the stem. A pair of stipules. The glandular hairs on marsh woundwort. Draw the detail in a circle in the corner of the page and label it. These small structures are what keys rely on, and what a photograph loses.

Notes on colour, taste and smell before they fade

Write colour in words as you draw, not later. "Pink" is useless; "pale rose with darker veins and a yellow eye" is usable. Note where the colour sits — petal tips, centre, the underside of a leaf, the flush on a young stem. A small colour patch in watercolour pencil is a bonus, but the written note should come first.

Smell is a legitimate field note for many wetland plants. Crush a leaf of water mint between your fingers and describe it. Nip a leaf of bog myrtle. Taste can confirm a plant too, but only taste what you know, and never taste anything you cannot identify with certainty.

Finish every page with the same four facts: date, grid reference, weather and habitat. A sketch without them is a nice drawing. With them, it is data.

Making the habit stick

Give each plant one page and a simple layout: the whole plant at a comfortable size, one flower from the side and one from above, a stem cross-section, one hand-lens detail, and the habitat scribble behind. Date and place in the corner. Working to the same template means you can compare two pages at a glance.

The reward comes with return visits. Sketch a clump of water mint in June in flower, and again in September in seed. Draw the same bogbean patch as the leaves unfurl in April and as they blacken in autumn. Your notebook slowly becomes a local flora with a memory.

Start small. Take the notebook and pencil on your next walk along a canal or through a wet meadow. Sit down. Draw one leaf, badly. The second one will be better.