the genus rebutia 1895—1981 - Free

companulate ->
campanulate
Analytical key to the Rebutia Sections
For reasons which have been explained, this key will not separate those species
which bridge the gap between the different sections i.e. those species with
intermediate characters. It should nevertheless help to delimit the majority of
species. It is based on a key published by Krainz (1967) and amended by B. Fearn.
A Body globular or cylindrical with the tubercles arranged on distinct ribs,
which may be vertical or spirally arranged. Body often suffused with
amethyst particularly during the winter months.
B Body cylindrical, flowers broad funnel-shaped to campanulate. Flowers
self sterile. Section II Mediolobivia Subsection II Cylindrorebutiae
BB Body globular or short cylindrical, flowers narrow funnel shaped,
lower part of receptacle usually fused with the base of style. Flowers self
fertile. Section III Digitorebutia
C Body obviously cylindrical, spines less than 5mm long, strongly
appressed, areoles arranged in vertical rows.
Section III Digitorebutia Subsection I Pygmaeae
CC Body globular, spines 5mm. or longer, always slightly erect never
appressed, areoles arranged spirally, occasionally in vertical rows.
Section III Digitorebutia Subsection II Euanthemae
AA Body globular to flattened globular, with indistinct ribs. Body green. Plants
usually densely spined.
C Receptacular scales with hairs and bristles, seeds ± earth coloured.
D Style not fused to the base of the receptacle.
Section II Mediolobivia Subsection I Setirebutiae
DD Basal portion of style usually fused with the lower portion of the
receptacle. Section I Aylostera
CC Receptacular scales naked (i.e. without hairs and bristles). Seeds black
and glossy, dome shaped usually with a prominent white basal hylum
area. Section IV Rebutia
E Flowers self fertile. Subsection I Rebutiae
EE Flowers self sterile. Subsection II Mediorebutiae
It is beyond the scope of this booklet to include a workable species key.
Flowers
All species in the genus Rebutia are day flowering and insect pollinated. Most
species are self fertile with the notable exception of 2 groups - Section II
Mediolobivia and Section IV Subsection II Mediorebutiae.
In Europe, Rebutias flower in late spring usually during the months of April and
May. The first species to flower is Rebutia marsoneri which usually flowers at the end
of February and beginning of March. It is thus one of the heralds of Spring.
Occasionally it flowers much earlier than this and on one notable occasion a plant of
this species was in flower at Abbey Brook on Christmas Day morning. The last plants
to flower are some members of Section I Aylostera such as R. deminuta, R.
pseudodeminuta and R. fiebrigii. There appears to be a distinct sequence in the
flowering of these plants. This time sequence may be of great biological significance
because in habitat it would maintain biological isolation even when the plants were
growing in close proximity to each other.
7
hylam ->
hylum