Showing posts with label SEM images. Show all posts
Showing posts with label SEM images. Show all posts

Tuesday, August 03, 2010

Key to the genus Lophophora sensu Šnicer et al.

In the article The Littlest Lophophora Šnicer, Bohata and Myšák detail the discovery of the new species Lophophora alberto-vojtechii and expand on the description originally given in the June 2008 issue of Cactus & Co.

The article also gives a key to the species of Lophophora which are divided into two sections Lophophora and Diffusae. These sections were originally introduced by the same authors in the booklet Genus Lophophora Coulter - Kaktusy special 2, 2005 and the division was based primarily on chemical composition but also on other factors like habitat, incompatibility of the species, rib numbers and morphology. Members of the Lophophora section are characterized by having concentrations of the psychotropic (mind-altering) alkaloid mescaline ranging from 15–30% of the total alkaloid content, while members of the Diffusae section contain a maximum of 1.3% mescaline. Šnicer et al. recognize five species of Lophophora.

SECTION LOPHOPHORA
L. williamsii (Salm-Dyck) Coulter


SECTION DIFFUSAE
L. diffusa (Croizat) Bravo
L. fricii Habermann
L. koehresii (J. Ríha) Bohata, Myšák & Šnicer
L. alberto-vojtechii J. Bohata, V. Myšák & J. Šnicer

The following key to the species of Lophophora assumes that L. alberto-vojtechii is allied with the non-mescaline-prevalent species, i.e. it is placed in the Diffusae section.

KEY TO THE SPECIES OF LOPHOPHORA
115–30% mescaline in total alkaloids, epidermis tough and thickSection Lophophora, L. williamsii
1Maximum 1.3% mescaline in total alkaloids; thin, fine epidermisSection Diffusae, 2
2Seed hilum wide (almost circular), testa not nodulated but reticulatedL. koehresii
2Seed hilum V–shaped, testa nodulated (outer cell walls protruding), individual testa cells clearly demarcated3
3Usually five (rarely eight) ribs, stem solitary in nature, miniature (rarely exceeding 25 mm in diameter)L. alberto-vojtechii
3Up to 21 ribs, stem solitary or branching in nature4
4Flowers dirty white with touch of yellow (rarely pinkish); fruits white to dark pink, usually pale pink; occurring in Queretaro, MexicoL. diffusa
4Flowers usually light pink to dark purple-pink, also white; fruits pink to dark purple-pink (when flower is white the fruit is always dark purple-pink); Coahuila, MexicoL. fricii

Seed morphology is an important factor in the above key. In their original publication on Lophophora alberto-vojtechii Šnicer et al. included SEM images illustrating the differences between the seeds of the various Lophophora species, these images along with their description are included below (Šnicer et al. attribute the SEM images to Gerhard Köhres; the images below are not scanned from the article but based on the ones included in the online French version of the article - just to make sure that credit is given where credit is due ;-)


Lophophora koehresii seed SEM images
Lophophora koehresii seed SEM image, side view (enlarged x50)Lophophora koehresii seed SEM image, hilum (enlarged x60)
Lophophora koehresii seed SEM image, detail of testa cells (enlarged x350)Lophophora koehresii seed SEM image, detail of testa cells (enlarged x800)
L. koehresii has a seed testa structure that is completely different from the other lophophoras. The hilum is wide open, and is almost circular. The testa is not nodulated (the outer cell walls do not protrude above the surface of the seed), but is reticulated [characterized by or having the form of a grid or network], and the cell walls are flat to even. The individual cells of the testa almost merge together. The seed in the pictures is from San Francisco in San Luís Potosí.


Lophophora alberto-vojtechii seed SEM images
Lophophora alberto-vojtechii seed SEM image, side view (enlarged x56)Lophophora alberto-vojtechii seed SEM image, hilum (enlarged x50)
Lophophora alberto-vojtechii seed SEM image, detail of testa cells (enlarged x350)Lophophora alberto-vojtechii seed SEM image, detail of testa cells (enlarged x800)
L. alberto-vojtechii has round black seeds, 1.15 to 1.45 mm long and 1.0 to 1.45 mm wide. The hilum is compressed into a broad V shape. The perimeter of the hilum consists of a pronounced edge. The testa is nodulated with the outer cell walls protruding. The individual cells of the testa are clearly demarcated. The seed in the pictures is from the type location in San Luís Potosí.


Lophophora fricii seed SEM images
Lophophora fricii seed SEM image, side view (enlarged x50)Lophophora fricii seed SEM image, hilum (enlarged x60)
Lophophora fricii seed SEM image, detail of testa cells (enlarged x350)Lophophora fricii seed SEM image, detail of testa cells (enlarged x800)
L. fricii has oval seeds, 1.5 mm long and 1.2 mm wide with the hilum compressed into a V shape. The testa is black, relatively coarsely nodulated, with an oval tubercle structure; the tubercles get smaller near the hilum. The individual cells of the testa are clearly demarcated. The seed in the pictures is from El Amparo in Coahuila.


Lophophora diffusa seed SEM images
Lophophora diffusa seed SEM image, side view (enlarged x50)Lophophora diffusa seed SEM image, hilum (enlarged x70)
Lophophora diffusa seed SEM image, detail of testa cells (enlarged x350)Lophophora diffusa seed SEM image, detail of testa cells (enlarged x800)
L. diffusa has seeds which vary greatly in terms of shape and size. The hilum is compressed into a broad V shape. The testa is coarsely nodulated with the outer cell walls protruding. The individual cells of the testa are clearly demarcated. The seed in the pictures is from Niñas Las Palmas in Querétaro.


Lophophora williamsii seed SEM images
Lophophora williamsii seed SEM image, side view (enlarged x50)Lophophora williamsii seed SEM image, hilum (enlarged x60)
Lophophora williamsii seed SEM image, detail of testa cells (enlarged x350)Lophophora williamsii seed SEM image, detail of testa cells (enlarged x800)
L. williamsii has seeds that are 1-1.5 mm long and black. The hilum is compressed into a broad V shape. The testa is nodulated with the outer cell walls protruding. The individual cells of the testa are clearly demarcated. The seed in the pictures is from Mazapil in Zacatecas.

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