Leuchtenbergia principis

Name and distribution

Leuchtenbergia principis is the accepted species name, published in 1848. Plants of the World Online defines its natural range as northeastern Mexico extending towards Jalisco. It grows in the desert and dry scrub biome. The earlier name Anhalonium leuchtenbergii refers to the same taxon. [2-WWW]

Britton and Rose described sites on limestone and shale substrates in the mountains of Coahuila, including Sierra de la Paila. In their account, other cacti and agaves grow alongside the plants. Among the agaves, the slender tubercles and pale spines give Leuchtenbergia a similar outline. These are historical field observations from selected Mexican sites. [Britton and Rose 1922]

Stem, tubercles and root

The stem axis elongates with age, and its lower part becomes woody. Tubercles are bluish-green, spirally arranged and approximately triangular in cross-section. In the monographic description, they reach 10–12,5 cm long. Their lower, older rows gradually die, leaving broad scars on the exposed stem. The plant produces a large taproot that may branch. [Britton and Rose 1922]

Each tubercle ends in an areole with a group of thin spines. The monograph distinguished 8–14 radial spines about 5 cm long and one or two central spines, sometimes up to 10 cm. Dense wool occurs between the tubercle bases. The spreading tubercles give the plant a broad, three-dimensional habit, while the actual stem axis remains much narrower. [Britton and Rose 1922]

How a papery spine forms

A flattened spine develops through a broad, thin meristem at its base, a region of dividing cells. New cells elongate, produce lignified walls and die. In L. principis, this produces a flexible, papery structure. The green tubercle, by contrast, is a projection of the stem with an areole at its tip. [Mauseth 2006]

Flowers and seeds

Flowers are funnel-shaped, yellow and fragrant. They arise singly just below the ends of young tubercles, near the centre of the plant. Britton and Rose described flowers lasting several days and reaching about 10 cm wide when fully open. Outer tepals may have a reddish tint and a darker stripe, while the inner tepals are oblong with a pointed tip. Seeds are dark brown with a finely papillose surface. [Britton and Rose 1922]

Fragment genu dehydryny

In 2017, Hernández-Camacho et al. obtained fragments of dehydrin gene sequences from Leuchtenbergia principis, Opuntia ficus-indica and Mammillaria bombycina. Material came from a bank of plants maintained in vitro. Dehydrins are proteins associated with the response to dehydration. The study compared DNA sequences and the resulting predicted characteristics of part of the protein. [Hernández-Camacho et al. 2017]

The Leuchtenbergia fragment contained sequences corresponding to three K segments, characteristic dehydrin motifs, and a histidine-rich region. The analysis predicted a hydrophilic, acidic and largely disordered protein fragment. Similarity to the described opuntia dehydrin was about 96–97%. Such data help identify members of this gene family and compare their relationships. [Hernández-Camacho et al. 2017]

The study did not measure transcript abundance during drought or protein concentration in the stem. The behaviour of Leuchtenbergia cells during dehydration therefore remains a separate physiological level. Detecting and comparing a gene fragment documents a potential component of this response, whose contribution requires studies of expression and the function of the full protein. [Hernández-Camacho et al. 2017]

Related articles

Materials from the author's archive

The species also appears in Konrad Szychowski's private material archive. [Kaktologia 2009b, file p. 12] [Neciu b.d., file p. 1]