New Gasteria cultivars

Ernst van Jaarsveld

Members of the genus Gasteria have horticultural appeal.
It is their attractive mottled, green (light to very dark, almost
blackish green) to glaucus leaves in a rosette and ease
of growth and propagation which makes them appealing. The
flowers are secondary, but some quite large (in relation to plant
size) and attractive. The leaf texture is also very variable, ranging
from smooth and shiny to tuberculate. Most species are small to
medium sized, shallow-rooted, thrive best in partial shade, and
ideal for indoor pot culture. Gasteria is closely related to Aloe
and Haworthia and inter-generic hybrids are known. Gasteria in
comparison to Aloe and Haworthia is very slow-growing and the
plants discussed below are all more than 10 years old. When
under stress, Gasteria leaves often turn reddish. In habitat most
Gasteria plants grow in the shade of thicket or karoo vegetation
whilst Aloe plants usually grow in full sun. Gasterias are readily
grazed whilst aloes, with bitter sap or thorny defense, are not.
Gasteria plants are well-camouflaged due to their mottled leaves
blending into the vegetation.
The Gasteria cultivars below are mostly the result of a hybridization
programme at Kirstenbosch National Botanical
Gardens. The hybridization experiments started in the late
eighties, testing their inter-species fertility. In preparation to
the Gasteria book (1994) all species (various forms from many
locations) were cultivated at Kirstenbosch and illustrated. All
known 13 species (at the time) were hybridized with each other.
All crosses were fertile and the results were more than a
hundred crosses. One of these hybrids, G. croucheri × G. pillansii,
yielded yellow flowers! The plants below represent selections
of some of these hybrids.

Methods
Gasteria flowers are protanderic (pollen first becomes ripe, then
contract whilst the stigma elongates). Most Gasteria species are
self-infertile and pollen from another genotype (genetic form)
has to be used to ensure seed-set. In habitat plants are pollinated
by sunbirds (Nectarinia spp.). The bird perches on the
scape (stem of the inflorescence) and pushes its thin elongated
beak into the opened flower tube, using its tongue to obtain
nectar. The dorsal side of the beak comes in contact with the
pollen and when the bird flies to another plant repeating the
process, pollen is rubbed against the stigma, and pollination is
accomplished. The artificial tool used was a match stick. Once
the pollen was shed, it was rubbed off onto the match stick,
and transferred to the ripe stigma of other species. The stigma
when ripe becomes extended and moist at the apex at the right
time for pollination. Each pollinated flower was marked with
a jewellery tag and the detail of the ‘father’ and ‘mother’ plant
added. Although each Gasteria species has its specific flowering
time which limited the pollen transfer to some other species
(especially eastern and southern Cape species originating
from a year round rainfall), many flower out of season, allowing
pollen transfer. Fortunately a large collection was built up
over the years and individuals flowering out of season were
used. Fertilization results are rapid; the ovary swells and the
initially pendent pedicel becomes ascending. If pollination was
not successful, flowers are aborted early. The ovary continues
to swell, eventually shedding the floral segments, and moved
to an erect position. Once ripe, the fruit becomes dry and the
capsule opens from the apex, exposing the flattened black
seed. The fruits are held in an erect position and needs strong
wind gust to dislodge the seed, thus they are well-adapted to
only release the seed when the wind velocity is strong enough
to scatter the seed over a large area. The infrutescences were
collected once the capsules started dehiscing. The seed was
stored in dry paper bags. Once dried, the capsules were broken
and the seeds extracted. Under normal conditions, seeds will
remain fertile for up to a year. However it can be stored in a
fridge and its rack life can be extended. Some plants were also
crossed with aloe, but not as successfully and only two crosses
were fertile. G. excelsa × A. ferox and G. bicolor × Aloe tenuior.

Sowing the seed
Seeds were sown when fresh in standard seed trays and standard
succulent plant mixture (2 parts sand, 1 part compost, 1 part
garden soil). Once sown, the seeds were lightly covered with
sand and moistened. A fungicide was used to prevent Pythium
fungal rot. Seeds were sown during spring or summer and germination
usually occurred within 3 weeks. Care was taken not
to over-water plants, and during winters watering was rapidly
decreased. The plants grew readily and some flowered for the
first time after 3 years. The plants were transplanted once large
enough to handle and transferred to small containers and kept
in a shady position. Gasterias are fortunately easily grown from
leaf cuttings or side shoots, and when a special cross is spotted,
it can be easily grown and increased, thus obtaining material
identical to the parent plant. In their native habitat Gasteria
grows in thicket vegetation and is adapted to cope with animal
abuse and grazing. The detached leaves on the ground are
adapted to root-sprouting and proliferating new stems.

Caring for the plants
The secret to successful growing is regular attention. The
growing medium should be porous (sufficient drainage holes)
and placed in a shady, but warm position. Although plants
will grow and survive in the same soil for years, they do respond
well to organic fertilizers during spring and summer
and repotting when necessary. G. pillansii is the only true winter
rainfall species and should be kept dry during summer. Although
Gasterias are almost problem-free they are susceptible
to fusarium root rot. Too much sun will also cause tissue damage.
Some species are fairly tolerant but needs hardening off
(gradual transfer from shade to sun).

Results
Although a multitude of hybrids were amassed, only a small
fraction was suitable for the horticultural industry. The various
combinations were interesting, some very easily grown
whilst others very susceptible to fungal pests. Plants were
chosen for their rosette size, compactness and shape. Leaf colour
and texture are also important, as is hardiness to diseases.
Best cultivars were obtained from using the following species:
Gasteria batesiana, G. batesiana var. dolomitica, G. ellaphieae, G.
armstrongii, G. glauca, G. bicolour var. liliputana, G. brachyphylla
var. bayeri, G. baylissiana, G. carinata, G. excelsa ‘Cala’ and G.
rawlinsonii. One of the individuals, a cross between G. croucheri
and G. pillansii yielded yellow flowers. The two inter-generic
hybrids between Gasteria and Aloe have been grown since the
early nineties but refuse to flower. These represent hybrids G.
excelsa × A. ferox and G. bicolor × Aloe tenuior.

Cultivar names
The sixteen Gasteria cultivar names below mainly reflect people’s
names. The Succulent Society of South Africa council
members and Editorial Committee members of their journal
ALOE, the Umdaus Press and Gariep Plants teams are recognized
for their work promoting succulent plants, so are the botanical
artists responsible for drawing Gasteria plants. The author’s
four children are also included. These Gasteria cultivars
are not registered and can be grown, shared etc. from cuttings
without any royalties. Cultivars not necessarily have to reflect
hybrids but variations within species are also selected. Small
forms of G. glomerata have also been selected and crossed with
other short-leaved plants resulting in very compact plants.

Gasteria ‘Kotie Retief’ (G. rawlinsonii × G. bicolor var. liliputana)
(named for Kotie Retief, previous president of the Succulent
Society of South Africa, member of the Editorial Committee of
ALOE, member of the Umdaus team, owner of Gariep plants)
Densely cluster-forming. Rosette 70 mm in diameter, proliferating
and forming dense clusters. Leaves lorate-triangular, 40
× 10 mm; surface dull mottled green; margin serrate-denticulate,
apex acute, mucronate.

Gasteria ‘Alex Fick’ (G. bicolor var. liliputana × G. rawlinsonii)
(named for Alex Fick, previous president of the Succulent Society
of South Africa, member of the Editorial Committee of
ALOE, member of the Umdaus team).
Rosette 120 mm in diameter, proliferating and forming dense
clusters. Leaves lorate-triangular 60 × 12 mm, mottled green
becoming reddish-green, margin sparsely denticulate, serrulate
towards end; apex acute, mucronata.

Gasteria ‘Francois Steffens’ (G. glomerata × G. baylissiana)
(named for prof Francois Steffens, editor of ALOE, member of
the Umdaus team)
Rosettes up to 80 mm in diameter, forming clusters. Leaves
remain distichous, lorate, 35 × 28 mm, surface densely whitetuberculate,
margin tuberculate; apex obtuse to retuse, mucronate.

Gasteria ‘Paul Brink’ (G. glomerata × G. pulchra)
(named for Paul Brink, previous president of the Succulent Society
of South Africa, member of the Editorial Committee of
ALOE, member of the Umdaus team)
Plants cluster-forming. Leaves distichous, rarely becoming rosulate;
surface dull- to whitish-green due to numerous white
tubercles in obscure transverse bands; margin tuberculate;
apex acute, mucronate.

Gasteria ‘Vicky Thomas’ (G. armstrongii × G. ellaphieae)
(named for the artist Vicky Thomas)
Rosette 100 mm in diameter. Leaves spreading, triangular, 40
mm × 20, surface sparsely tuberculate, olive-green, margin tuberculate-
serrulate; apex acuminate.

Gasteria ‘Tamlin Blake’ (G. batesiana var. dolomitica × G. batesiana var.
batesiana)
(named for the artist Tamlin Blake)
Rosette 180 mm in diameter. Leaves spreading, lorate, 80 × 25
mm; surface olive green, tubercles in transverse (zebra) bands,
margin denticulate; apex obtuse, mucronate.

Gasteria’ Lisa Strachan’ (G. ellaphieae × G. batesiana var. batesiana)
(named for the artist Lisa Strachan)
Rosette 160 mm in diameter. Leaves spreading, linear-triangular
80 × 16 mm, surface with dense grey, tuberculate, margin
denticulate; apex acuminate, mucronate.

Gasteria ‘Jeannette Loedolff’ (G. excelsa × G. carinata var. glabra)
(named for the artist Jeannette Loedolff)
Rosette 140 mm in diameter. Leaves ascending, spreading,
ovate, 80 × 28 mm, surface smooth, mottled green, margin tuberculate-
denticulate; apex obtuse, mucronate.

Gasteria ‘Sean Gildenhuys’ (G. glomerata × G. rawlinsonii)
(named for Sean Gildenhuys, member of the Editorial Committee
of ALOE, manager of Gariep plants)
Rosette 90 mm in diameter, cluster-forming. Leaves ascending,
spreading, lorate, 50 × 20 mm, surface light grey-green, faintly
mottled, margin sparely serrulate, serrulate towards end; apex
obtuse, mucronate.

Gasteria ‘Nic Drost’ (G. glauca × G. armstrongii)
(named for the late (Oom) Nic Drost, one of the founding
members of the Succulent Society of S.A. and Secretary for
countless years)
Rosette 90 mm in diameter. Leaves spreading, distichous becoming
spiral, triangular, ovate, 40 × 25 mm, acute, surface
grey-green, tuberculate, margin tuberculate-serrulate; apex
acuminate, mucronate.

Gasteria ‘Louisa’ (G. glauca × G. batesiana)
(named for the author’s daughter)
Rosette 110 mm in diameter. Leaves
spreading, triangular, 55 × 25 mm, acute,
surface grey-green, sparsely tuberculate,
margin entire, somewhat tuberculate;
apex acuminate.

Gasteria ‘Zaria’ (G. glomerata × G. batesiana var.
dolomitica)
(named for the author’s daughter)
Rosette 120 mm in diameter, densely
cluster-forming. Leaves spreading, becoming
recurved, lorate, 60 × 30 mm,
surface olive-green, densely white tuberculate;
margin tuberculate; apices
purplish, apex obtuse, mucronate.

Gasteria ‘Albert’ (G. glomerata × G. doreeniae)
 (named for the author’s son)
Rosette 75 mm in diameter, densely
cluster-forming. Leaves spreading,
distichous, lorate, 40 × 18 mm, surface
olive-green, slightly mottled, smooth;
margin dark green, entire, apex obtuse,
mucronate.

Gasteria ‘Henk’ (G. rawlinsonii × G. bicolor var. bicolor)
(named for the author’s son)
Rosettes 180 mm in diameter, proliferating
from the base, forming dense
groups. Leaves distichous, spreading,
lorate, 85 × 20 mm, surface mottled,
olive-green (becoming reddish green),
margin sparsely serrulate, apex obtuse
to subacute, mucronata.

Gasteria ‘Limelight’ (G. carinata var. verrucosa × G. baylissiana)
Rosette 190 mm in diameter, clusterforming.
Leaves ascending, spreading,
remaining disctichous, lorate, 100 × 40
mm; surface tuberculate, dark green
with yellowish, margin tuberculate; apices
obtuse, mucronate.

Gasteria batesiana ‘Black Beauty’
Rosette 300 mm in diameter. Leaves ascending,
spreading, lorate, 160 × 30 mm,
surface and margin black-green, apex
obtuse, mucronata.