Index of articles:
In 1871 Sir Joseph Hooker at Kew wrote, 'Of all cultivated plants none are more difficult to name accurately than the species of agave, partly because of the imperfection of published descriptions and more from the impossibility of fixing their characters by words'. The confusion and argument continues to this day and it is still not uncommon to see in collections and sales lists a particular name applied to plants that quite obviously have different features. I have good experience of this type of problem in that a particular plant in my collection labelled as agave warelliana has been 'positively' identified by a fellow enthusiast as being agave pedunculifera whilst I have seen an identical plant offered by a nursery online as agave attenuata v. serrulata and recently saw a photo from the Botanical Gardens in Amsterdam of this plant labelled as agave hartmanii. There are so many unresolved issues that agavologists will be kept busy for some time to come.
Linnaeus founded the genus in 1753 and recognised four species: americana; vivipara; foetida ( now moved to Furchraea ) and virginica ( now moved to Manfreda ). Most agave names were added in the 18th and 19th century and prominent amongst the experts at the that time were Salm-Dyck who revised the genus between 1834 and 1859 and ultimately described 45 species in 5 sections. This work was developed further by von Jacobi between 1864 and 1867 when he described 78 species and many varieties. The problems with these works and those of other authors at that time is that names were based on often immature potted plants grown in cultivation in various European collections in very non Mexican conditions. Slight variations in appearance, be it in the size of plant or shape of leaves, led to yet another species or variety being born and so to ever bigger lists. There was no scientific back up provided in the shape of illustrations or descriptions of preserved specimens. Baker in 1888 listed 138 species in 3 subgenera including Manfreda but although he was fortunate in that he was able to observe flowering agaves he did not use flowering characteristics in his classification. By this time illustration of the plants was relatively commonplace and was of great help to the taxonomists of the time and also to their successors. Prior to 1934 agaves were classified as Amaryllideae but at that time Hutchinson at Kew combined them with yuccas, manfredas, furchraeas, hesperaloes and others in the new family grouping of Agavaceae.
- 'The Big Three' as far as agave nomenclature was concerned were William Trelease, Alwin Berger and Howard Scott Gentry. Trelease was the director of the Missouri Botanical Gardens in St. Louis and was the first major taxonomist who travelled quite extensively in Mexico, the Caribbean and parts of South America and observed plants actually growing in the wild. He produced several works between 1907 and 1924 describing agaves both on the mainland and those of the various Caribbean islands. He made little use of floral characteristics in identifying species and continued the traditional taxonomy of the 19th century described by Gentry as the concept of 'out of difference comes species'.
- In Europe Alwin Berger organised the botany of agave in his great work 'Die Agaven' published in 1915. He described 274 species divided into 3 subgeneric groups, Littaea, Euagave and Manfreda, these being split further into sections and subsections. He tended to follow the traditional concepts in naming species although he did make some use of flowering characteristics at section level. He was the curator at the Hanbury Gardens in La Mortola near Ventimiglia in northwestern Italy, close to the French border. There was a rich living collection of plants growing here in a climate more favourable to normal development and maturation of agaves.
- These preceeding taxonomists can be described on the basis of the proliferation of agave names under their authorship as 'splitters'. In 1982 there appeared a mammoth work on agaves titled ' Agaves of Continental North America' by Howard Scott Gentry which was reprinted in 1998 with a few modifications. This is regarded now as the standard reference work on these plants although it does not cover the Caribbean area. Gentry names 136 species which with subspecies, varieties and forms total 197 taxa. There are 2 subgeneric groups, Littaea and Agave, divided on the basis of differing flower characteristics. Unlike his predecessors Gentry was very much a 'lumper' and fostered the broader species concept. He travelled widely and described plants on the basis of extensive work in habitat and he was also the first to make extensive use of flowering characteristics in nominating species. He also emphasised the fact that agaves are very variable in their growth characteristics and appearance may depend very much on geography and climate so that one cannot always take the appearance of a single plant at face value as the earlier European taxonomists tended to do.
Since Gentry the most prolific agave author is Bernd Ullrich who has written several important papers between 1990 and 1993 reassigning some names from Gentry's classification and also reassigning plants to different family groups on the basis of new evidence. He has also introduced 2 new family groupings into the subgenus Littaea.
- The Caribbean agaves, ignored by Gentry, were initially classified by Trelease in 1913 and included in his work by Berger. Further nomenclatorial work on these plants has been done by Dutchmen P. Waagenaar Hummelinck in a series of articles between 1936 and 1993 and D.O.Wijnands in 1983 plus R.A. Howard in 1979.
- I think that a very important point often forgotten ( perhaps too conveniently in some cases ) is the fact that there exist many intermediate forms between various agaves as well as many hybrid forms so that it is not always possible to place a plant in a specific category as defined by Gentry and other authors. As someone once pointed out to me ' Plants do not grow in habitat with labels on them ' and I think this is a very important and relevant statement. This is of course in addition to the fact that in Europe we may be trying to identify plants grown in pots and in very non habitat like conditions. The group Marginatae is especially difficult in this respect with a proliferation of various hybrids and intermediate forms making life very difficult and quite confusing for those trying to name individual plants. Agave victoria-reginae for example mixes readily with agave scabra (= agave nigra ) and with lechuguilla (= agave victoriae-reginae f. viridis), whilst lechuguilla itself is involved in many mixed forms with agave lophantha. Lophantha in turn mixes readily with various forms of ghiesbreghtii and xylonacantha, many of these plants being given new names eg. agave simonii ( = lechuguilla X xylonacantha ). Agave filifera and schidigera have also been involved in various mixes giving rise to agave leopoldii ( = filifera X schidigera ) and agave taylorii ( = filifera X geminiflora ). A recipe for confusion if ever there was one !!!
For me a classical example of categorising a plant erroneously is the plant illustrated above, with shiny green leaves and pale median stripe. This I have seen many a time wrongly labelled Agave obscura when it appears in fact to be a form of Agave lophantha or possibly an intermediate form of the latter with Agave ghiesbreghtii or xylonacantha. The true Agave obscura as originally described by Schiede in 1830 is quite different and has recently been considered as the same plant as Agave polyacantha v. xalapensis. ( See below ** ).
- There is also a plant doing the rounds as Agave titanota ( see above picture ) but is quite unlike the plant defined by Gentry ( which has grey-white leaves ) and it appears to be a form possibly belonging somewhere else in the ever difficult Marginatae group. However it has been found growing near to the true titanota and could represent a variant.
- This plant is also sold as sp. Sierra Mixteca FO-076 and sp. Nr.1.
Agave titanota ( the real thing)
This subgenus is recognised by Gentry (1982) on the basis of a spicate inflorescence where the flowers cling to the stalk in pairs or clusters.
Gentry organised this subgenus into 8 groups comprising 54 species and a total of 71 taxa including subspecies, varieties and forms. Since then a number of revisions have been made primarily by Ullrich.
Important changes proposed since Gentry (1982) :
Agave bracteosa transferred from Choripetalae group to new Serrulatae group ( Ullrich 1990d) :
Agave hartmanii identified as synonym of agave parviflora ssp. flexiflora (Ullrich 1990i) :
Agave attenuata and pedunculifera regarded as part of the same variable complex ( Ullrich 1990d) :
Agave stricta reclassified as subspecies of agave striata ( Ullrich 1990b ; 1991d) :
Agave colimana reverts back to agave ortgesiana ( Ullrich 1991a) :
Agave nizandensis transferred from Amolae group to new Nizandensae group ( Ullrich 1991b) :
Agave felgeri transferred from Filiferae group to Parviflorae group ( Ullrich 1991c) :
- Agave multifilifera and agave schidigera reclassified as subspecies of agave filifera ( Ullrich 1992 l) :
- Agave obscura is identified as synonymous with agave polyacantha v. xalapensis ( Chazaro- Basanez 1981 and Ullrich 1992 ). See below **
- Agave celsii considered as synonym for Agave mitis ( Ullrich 1993a )
- Agave warelliana, belonging to the Polycephalae group, found for the first time as a wild plant at the Pico de Oriba volcano in Veracruz . Found also at La Trinitaria, Chiapas, Mexico by Garcia Mendoza . Previously the plant had been described by Baker from a specimen at the Reigate collection of Mr. Wilson Saunders. The neotype specimen had been designated by Gentry in 1982 from a plant from the Hanbury Gardens at La Mortola prepared by Berger in 1912.
Ag. warelliana in habitat © Abisaí García Mendoza © Missouri Botanical Garden - Newly named species :
- Agave horrida ssp. perotensis from Puebla and Veracruz, Mexico ( Ullrich 1992 d) :
- ** The original agave obscura was named by Schiede in 1830. Subsequently it was ignored in turn by all the famous taxonomists such as Salm Dyck, Jacobi, Baker and Berger. The name was mentioned again by Trelease, Breitung and Gentry but appears to have referred to a different plant ,closely related to agave horrida and named by Ullrich as agave horrida ssp. perotensis. Schiede's original agave obscura is considered in work by Chazaro Basanez 1981 and Ullrich 1992 as the same plant as agave xalapensis which Gentry treated as a variety of agave polyacantha. Ullrich further proposes that the name polyacantha is a ' nomen confusum ' and should no longer be used
- Agave tenuifolia from Sierra Madre Oriental, Mexico related to A. striata ssp. striata ( Zamudio- Ruiz & Sanchez- Martinez 1995) :
- Agave filifera ssp. microceps from Sinaloa, Mexico ( Kimnach 1995) :
- Agave wendtii from Sureste de Vera-Cruz, Mexico related to A. pendula ( Chazaro-Basanez 1995) :
- Agave petrophila from Guerrero and Oaxaca, Mexico related to A. dasylirioides, originally named A. gracilis but subsequently renamed by the authors ( Garcia Mendoza & Martinez Salas 1998) :
- Agave garciae-mendozae from Hidalgo, Queretano and San Luis Potosi, Mexico; belonging to the Marginatae group, closely related to A. horrida and A. kerchovei ( Galvan & Hernandez 2002 )
- Agave hidalgensis from Hidalgo, Mexico; belonging to the Marginatae group ( Galvan & Koch 2002 )
- Agave vazquez-garciae from Sierra Manantlan, Jalisco. Belongs to Amolae group and closely related to A. pedunculifera. ( Chazaro-Basanez & Pelayo 2002 ).
- Agave rzedowskiana from Jalisco and Sinaloa, Mexico; belonging to the Striatae group, similar to A. dasylirioides and A. petrophila. ( Carrillo-Reyes, Avina & Ramirez-Delgadillo 2003 )
- Agave gomez pompae from Cordoba in Veracruz,Mexico. First discovered in 2004 and subsequently described by Chazaro and Jimeno-Sevilla. It belongs to the the family group Polycephalae. It's closest relative is agave pendula
- Agave albopilosa from Sierra Madre Oriental ( Cabral, Villareal and Estrada 2007). It belongs to the subgenus Littaea and family group Striatae. A distinguishing feature is a ring of hairs growing near the tip of each leaf, below the terminal spine.
- Agave arcedianoensis ( originally Agave colimillensis ) ( Chazaro, Valencia and Vazquez 2007) ; a close relative of. of agave angustiarum. Found in Colimilla and Rio Verde, Jalisco.
- Agave chazaroi from Tequila,Jalisco, described by Vazquez in 2007. There are grounds to believe that this plant may be the long lost agave bakeri.
This subgenus is recognised by Gentry (1982) on the basis of a paniculate inflorescence where the flowers appear in clusters on lateral branches. Previous authors had used the name Euagave.
Gentry organised this subgenus into 20 groups comprising 82 species and a total of 126 taxa including subspecies, varieties and forms. Since then a number of revisions have been made by various authors.
Important changes proposed since Gentry (1982) :
Agave macroculmis [Todaro] as assigned by Gentry to wild plants in habitat is now considered incorrect ( he himself had doubts, p.601 ) and Todaro's plants have been identified as a form of agave atrovirens. The wild plants that Gentry gave this name to are now considered as a new species and named Agave gentryi (Ullrich 1990b) :
Agave angustifolia is renamed as agave vivipara ( Wijnands 1983 ; Foster 1992 ; Smith & Steyn 1999). As yet this change has not been widely accepted.
Agave scabra [Salm-Dyck] as allocated by Gentry was corrected to agave asperrima [Jacobi]. From descriptions and photographs it was shown that Salm-Dyck's original plant was agave wislizeni {Engelmann], nowadays considered a form of agave parryi. The name scabra had earlier been used by another author, Ortega in 1797, to describe a plant subsequently reassigned to Manfreda so Salm-Dyck's use for his plant was invalid. ( Ullrich 1992):
Agave parryi v. couesii / huachucensis / truncata were all reclassified as forms of agave parryi ssp. parryi ( Ullrich 1992) :
Agave neomexicana was reclassified as a subspecies of agave parryi ( Ullrich 1992) :
Agave wislizeni was reclassified as a synonym for a form of agave parryi and no longer applicable to agave parrasana ( Ullrich 1992) :
Agave pygmaea reclassified as subspecies of agave seemanniana ( Ullrich 1992c) :
Agave deserti ssp. pringlei (Engelmann ex Baker) Gentry becomes Agave deserti var. pringlei (Engelmann ex Baker) and Agave deserti ssp. simplex (Gentry) becomes Agave deserti var. simplex (Gentry) i.e. the two subspecies Gentry recognized under Agave deserti are reduced to variety status { Hodgson 2001 ) :
Newly named species :
- Agave grijalvensis from Chiapas, Mexico belonging to the Marmoratae group ( Ullrich 1990a) :
- Agave tequilana cv. Limeno ( Kimnach & Trager 1991) :
- Agave isthmensis from Chiapas and Oaxaca, Mexico related to A. potatorum and A.seemanniana v. pygmaea ( Garcia-Mendoza & Palma 1993) :
- Agave delamateri from Arizona (Hodgson & Slauson 1995) :
- Agave montana from Mexico classified in the Salmianae group ( Villareal 1996) :
- Agave phillipsiana ,a new freely suckering species allied to A.palmeri and A.delamateri and found only in four sites within the Grand Canyon National Park in Arizona, ? a hybrid between A.palmeri and A.americana var. expansa ( Hodgson 2001 ) :
- Agave x ajoensis, ? a sterile hybrid between A.deserti var. simplex and A.schottii var. schottii, found only in the Ajo mountains in the Organ Pipe National Monument, Arizona ( Hodgson 2001 ) :
- Agave ovatifolia, from Nueva Leon, Mexico; a new species belonging to the group Parryanae and related to A.parrasana and A. havardiana ( Starr & Villareal 2002 ):
- Agave valenciana from Jalisco, Mexico; belongs to the Marmoratae group, closely related to A. marmorata. ( Chazaro& Vazquez 2005 )
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Named Hybrids.
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There is an excellent series of articles on agave nomenclature called ' Agaven : What's in a name' by Dr. Peter Kuppen ( in Dutch) in 'Succulenta', Journal of the Belgian / Dutch Cactus Society in vols. 78 (nrs. 4,5,6) and vols. 79 (nrs. 2,3) with a very useful selection of the relevant reference literature.
