Strombocactus

Strombocactus is a monotypic genus with a strong turnip-like root, a small, depressed, roughly spherical stem covered with spirally arranged overlapping tubercles, each with a spine-bearing areole at its tip.

Strombocactus disciformis are low-growing, gray-green succulents with a broadly round, unbranched stem and root. In their natural habitats, they grow in a disk shape, half hidden in the ground, reaching around 8 cm in diameter and 2-3 cm in height. In cultivation, they become nearly spherical. Adult tubers can reach 15 cm in diameter, larger than the above-ground parts. The plant's spiral ribs are deeply notched, creating a wart-like appearance with a ratio close to the golden ratio (13:8). Areoles are located on the blunt ends of these warts, which are curved (straighter in cultivation) and have a square base. They rarely have more than four or five short, bristly thorns, which fall off after a few years.{{cite book | last1=Anderson | first1=Edward F. | last2=Eggli | first2=Urs | title=Das grosse Kakteen-Lexikon | publisher=Ulmer | publication-place=Stuttgart (Hohenheim) | date=2005 | isbn=3-8001-4573-1 | language=de | pages= 607–608}}

Flowers come from new growth at the crown, emerging from the youngest areoles. The flowers, white to cream or magenta and 2.5 to 3.5 cm long and open to about 4 cm in diameter. The 7 mm long, thin-walled brown fruits contain 0.3 mm reddish-brown seeds.{{cite book|last1=Venning|first1=Frank D.|title=Cacti (A Golden Guide)|publisher=Western Publishing Company, Inc.|location=Racine, Wisconsin|page=155}}

File:Strombocactus disciformis-IMG 3554.JPG|Growth habit

File:Strombocactus disciformis.jpg|Flowers

File:Strombocactus disciformis-IMG 3561.JPG|Spines

File:Seedling of Strombocactus disciformis.jpg|Seedling

File:Strombocactus disciformis - Pena Blanca.jpg|View of plant from the top

The species has two recognized subspecies:{{cite web | title=Strombocactus disciformis (DC.) Britton & Rose | website=Plants of the World Online | url=https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:246156-2 | access-date=2024-06-11}}

Strombocactus disciformis is found in the Mexican states of Querétaro, Hidalgo, and Guanajuato, growing on almost vertical, weathered limestone rocks at altitudes of 1000 to 1600 meters.{{cite web | last=Vallicelli | first=Valentino | title=Strombocactus disciformis | website=LLIFLE | date=2013-08-04 | url=http://www.llifle.com/Encyclopedia/CACTI/Family/Cactaceae/2103/Strombocactus_disciformis | access-date=2024-06-11}}{{Creative Commons text attribution notice|cc=bysa3|from this source=yes}}

File:Strombocactus disciformis (5780129599).jpg|Plant growing vertically in habitat in Pena Blanca, Queretaro

File:Strombocactus disciformis (5780702818).jpg|Plants growing on rocks in Pena Blanca, Queretaro

File:Strombocactus disciformis (5780683148).jpg|Plant growing with Mammillaria parkinsonii

File:Strombocactus disciformis BlKakteenT39a.jpg

First described as Mammillaria disciformis by Augustin-Pyrame de Candolle in 1828, the specific epithet disciformis is derived from the Latin "discus" (disc) and "-formis" (shaped), referring to the plant's shape.{{cite web | last1=D&Amp | first1=Um National | last2=(France) | first2=histoire naturelle | title=Mémoires du Muséum d'histoire naturelle | publisher=G. Dufour | volume=t.17 (1828) | date=1828 | url=https://www.biodiversitylibrary.org/page/35009717 | access-date=2024-06-11}} Nathaniel Lord Britton and Joseph Nelson Rose reclassified it as Strombocactus in 1922.{{cite book | last1=Britton | first1=Nathaniel Lord | last2=Eaton | first2=Mary E. | last3=Rose | first3=J. N. | last4=Wood | first4=Helen Adelaide | title=The Cactaceae : descriptions and illustrations of plants of the cactus family | publisher=Carnegie Institution of Washington | publication-place=Washington | year=1919 | doi=10.5962/bhl.title.46288 | page=}}

Both subspecies are [http://www.iucnredlist.org/details/152318/0 classified as Vulnerable] on the IUCN Red List, which states that it has a limited range and "is experiencing a decline in mature individuals due to illegal overcollection". The species is listed in Appendix 1 of the Convention on International Trade in Endangered Species meaning commercial international trade is prohibited and non-commercial international trade is regulated.

{{Reflist}}

• {{Commons category-inline|Strombocactus|Strombocactus}}
• {{Wikispecies-inline|Strombocactus|Strombocactus}}

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Category:Cactoideae

Category:Monotypic Cactaceae genera

Category:Flora of Mexico