Pygmy sundew gemmae: collecting, sowing and mailing them

What a gemma is

Pygmy sundews are tiny rosettes, typically 15 to 20 mm across, with some larger species reaching 50 mm. The ICPS counts over 50 species, almost all from southern Western Australia ^[2]. Most live where winters are wet and summers dry. They grow and flower through winter and spring, survive summer as a bud of stipules above ground, and in fall those buds release gemmae before the new winter leaves appear. Gemmae let the plants reproduce without seed and spread a short distance ^[2].

Each gemma is a modified leaf holding a small growth bud: a few tiny leaves wrapped around the growing point and the red stub of a future root ^[1]. Drosera scorpioides, one of the largest pygmies and the easiest to harvest, is a typical example; FloraBase records it as native and not threatened in Western Australia, on sand, clay, laterite outcrops, swamps and sand ridges ^{[1, 3]}. Not every species makes gemmae. D. pulchella, from cooler, wetter places, generally does not form stipule buds, and the South American D. meristocaulis makes no gemmae at all ^[2].

Why gemmae are the method to use

The ICPS calls gemmae the easiest way to propagate pygmy sundews, and for some hybrids the only way ^[1]. The alternatives are poor:

• Leaf cuttings are impractical, because the leaves are thin and rarely sprout ^[4].
• Stem cuttings do not work, and the plants cannot be transplanted ^[1].
• Seed is limited. Most species set seed only when cross-pollinated with a different clone or species, the flowers produce little seed, and the hybrids usually make none ^[2]. A few, such as D. omissa, set seed on their own and are relatively easy from seed ^[2]; see sowing seeds.

Gemmae are also how old plants are renewed. With the years, pygmies can grow tall, with the stem buried in dead leaves ^[2]. The ICPS example is a D. scorpioides that had filled its pot for three years; since it could be neither moved nor cut, the only option was to start again from its gemmae ^[1]. The ICPS guide notes that some losses are normal, that most growers trade gemmae every fall, and that some start their collection over from gemmae each year ^[2]. For other sundews, see Drosera leaf cuttings.

Getting the plants to make gemmae

Light is the switch. Plants under the same day length all year usually grow well but neither flower nor make gemmae ^[5]. The ICPS gemmae page notes that its author’s plants grown outdoors in California made gemmae while those in his terrariums did not ^[1]. The guide recommends strong LED light on a timer that tracks local sunrise and sunset, or growing outdoors, where pygmies will probably do better than in a humid terrarium; indoors in winter they should stay on a natural light cycle ^[2]. With those cues, gemmae appear in late fall and early winter ^[1]. The light guide covers timers.

Prepare the pots first

Pygmy sundews have one very long, fragile root and usually die if it breaks, so the ICPS advises against transplanting them. Plant gemmae in the pot where you want the plants to live for good ^{[1, 2]}.

• Tall pots. The ICPS uses standard nursery pots 9 cm (3.5 in) square and 10 cm (4 in) tall ^[1].
• Sandy soil. The gemmae page recommends peat with 50% to 75% sand or perlite, leaning to the sandier end to discourage moss ^[1]. The growing guide suggests one part peat to two parts sand, or at least that much sand in the top 3 cm ^[2]. Once established, the plants tolerate a soil surface that stays dry ^[1]. See soil.
• Tools. A kitchen scoop to catch gemmae, forceps or another pointed tool, a dish to hold them, a spoon to level the soil, labels and a #2 pencil ^[1].

Collecting gemmae

There is no perfect method, and different species suit different ones ^[1].

1. Forceps and scoop. The ICPS author’s method: lay the pot on its side and knock the gemmae into a kitchen scoop with the tip of the forceps. Comb stuck gemmae off the leaves with the two tips held slightly apart. Work away from other mother plants, because some gemmae fly ^[1].
2. Plastic box. Lay the pots on their side in a clear plastic box and let the gemmae fall in, with a paper towel to soak up water that leaks out of the pots. Wet gemmae are awkward to handle, and sand ends up in the box ^[1].
3. Wet tip. Pick up individual gemmae on the moistened tip of a plant tag or bamboo skewer. This is slow, fails with large, thick gemmae such as those of D. scorpioides, and works only moderately with thin ones such as D. allantostigma ^[1].
4. Gemmae vacuum. A homemade suction device is another option ^[1].

D. scorpioides and ground-hugging D. roseana give up their gemmae easily, while the thinner, smaller gemmae of D. allantostigma tend to stick in the leaves ^[1].

Planting

1. Place the gemmae one by one, no closer than 1 cm apart. Space them for the plants’ whole lives: closer for a solid mat, farther apart to show each rosette ^[1].
2. Set them on the surface or bury them very slightly ^[2].
3. Either mist the surface lightly to settle them, or first sprinkle a thin layer of sand over them and then mist. The ICPS author prefers the sand, which holds gemmae in place and keeps them from drying out; it is unnecessary if the pots go straight into a terrarium ^[1].
4. Label the pot ^[1].

A bag is not needed, though high humidity for the first few weeks helps ^[2]. See terrariums and humidity. Success shows within a few weeks, when the red root stub grows down into the soil and the tiny leaves start to look like proper sundew leaves ^[1]. The ICPS publishes no success rate. Gemmae planted in spare pots of other plants can also grow on ^[1].

Keeping labels honest

Rain is the main cause of mix-ups. Raindrops striking plants with gemmae can throw them tens of centimeters, so gemmae end up in neighboring pots, and the ICPS says many traded gemmae are misidentified for this and other labeling reasons ^[2]. Protect plants carrying gemmae from rain; the ICPS photos show pots outdoors under a fiberglass panel for that purpose ^[2]. The guide calls moss the biggest problem in growing pygmies, and extra sand and outdoor sun help keep it down ^[2].

Mailing spares

Gemmae are small living plants, and the ICPS reports that gemmae sent in an empty bag or on a dry towel arrive dead ^[1].

1. Cut a heavyweight paper towel into squares; the gemmae page cuts each towel into nine ^[1].
2. Wet it, then squeeze out the excess without wringing it dry ^[1].
3. Put the gemmae in the middle, fold the towel in thirds, turn it over, and fold in thirds again ^[1].
4. Seal it in a clearly labeled plastic bag and ship in a padded envelope or small box ^[1].

The two ICPS pages differ on the towel. The gemmae page uses blue shop towels because they are heavier and mold less than kitchen paper; the growing guide recommends the kind found in restrooms, for the same reason ^{[1, 2]}. Both prefer their choice to ordinary kitchen towels. More on the genus is in the Drosera overview.