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On 10th May 2019 three members of the Lithops Research & Conservation Foundation visited the Lithops pseudotruncatella subsp. pseudotruncatella var. riehmerae colony on the farm Rietfontein with the aim of collecting information on the size, composition and health of the colony.

The strategy followed was to search for all plants in the colony and mark these by placing coloured disks temporarily close to the plants found and in addition mark all other succulent plants that grow in the same habitat. When we were confident that all the Lithops plants in the colony had been located and marked, the drone was activated, and aerial photographs of the colony were taken to record the position of every plant in the colony. The surface area of the colony was determined with the aid of a Garmin Oregon 700 GPS Reader area calculation function after measuring the circumference of the colony.

A total of 104 plants were found in the colony which consisted of 17 single-headed adult plants and 72 double-headed adult plants with 15 juvenile plants of two different age groups making up the rest of the population. In all, 53 % of all the adult plants had flowered. This contrasts with the 82 % of plants that flowered in the previous year when the rainfall was slightly higher. In the 22 m2 surface area of the colony there was 4.7 plants/m2. The drone image showed that most plants occurred on top of the small quartz outcrop and that the plants on the sides of the outcrop were established through seeds being passively washed down the drainage lines.

A small group of 10 plants grow on the southern slope of the outcrop 40 meters away from the main colony. Other data collected through the drone images whilst visiting the colony, such as the nearest neighbour distance between the plants and the size of the plants as recorded through the photographs taken of each plant, will be analysed within the next few weeks.

Most of the plants were in good condition although three plants displayed very recent damage to the leaves due to the cattle trampling them and two plants showed sunburn damage to the leaves. The damage to the leaves was not serious enough to cause the plants harm in the future. Anacampseros sp. and Kalanchoe sp. were the only other succulents growing in the Lithops colony.

The colony seems to be healthy and does not need any special management strategy at present.

The Foundation is grateful to Marc Riehmer for allowing us access to the colony and thus the opportunity to study these Lithops plants.

A typical Lithops pseudotruncatella p. riehmerae plant with old flowers and showing the characteristic unequal sized leaves on each head.

Two well camouflaged double headed Lithops pseudotruncatella p. riehmerae plants.

A Giraffe near the Lithops pseudotruncatella p. riehmerae colony seen during our visit on 10th May 2019. Giraffes do not graze on Lithops plants.

Members Janice Round and Marc Mougin flying the drone over the Lithops pseudotruncatella p. riehmerae colony to record the information about the colony size and distribution.

A young Lithops pseudotruncatella p. riehmerae plant.

Lithops p. pseudotruncatella riehmerae plants marked with blue disks each representing a head of a plant in the colony shows the distribution along the drainage line.

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