I am giving the following details from Factsheet:
Agave americana may be easily confused with the sisals (Agave sisalana and Agave angustifolia) and the false agaves (Furcraea foetida and Furcraea selloa). These species can be distinguished by the following differences:
  • A. americana has very large greyish or variegated leaves that are usually 1-2 m long on adult plants. These leaves have numerous, relatively large prickles (5-10 mm long) along their margins. Its flowers are borne in an upright position and are yellow or yellowish-green in colour. This species produces large capsules and usually doesn’t develop plantlets (bulbils) on the branches of its flower clusters.
  • A. sisalana (sisal) has relatively large dark green or greyish-green leaves that are usually 0.5-1.3 m long on adult plants. These leaves do not have any prickles on their margins. Its flowers are borne in an upright position and are yellow or yellowish-green in colour. This species usually doesn’t produce capsules, instead developing numerous plantlets (bulbils) on the branches of its flower clusters.
  • A. angustifolia (Caribbean agave) has relatively large green, greyish-green or variegated leaves that are usually 0.5-1 m long on adult plants. These leaves have many, relatively small prickles (2-5 mm long) along their margins. Its flowers are borne in an upright position and are yellow or yellowish-green in colour. This species produces large capsules and sometimes also develops plantlets (bulbils) on the branches of its flower clusters.
  • F. foetida (Cuban hemp) has very large pale green leaves that are usually 1-2 m long on adult plants. These leaves usually have some prickles along their margins, but mainly near the bases of the leaves. Its flowers are borne in a drooping position and are whitish or greenish-white in colour. This species doesn’t produce capsules, instead developing numerous plantlets (bulbils) on the branches of its flower clusters.
  • F. selloa (variegated false agave) has very large variegated leaves that are usually 1-2 m long on adult plants. These leaves have numerous relatively large prickles (7-8 mm long) along their margins. Its flowers are borne in a drooping position and are whitish or greenish-white in colour. This species doesn’t produce capsules, instead developing numerous plantlets (bulbils) on the branches of its flower clusters.

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18/05/2021 : surajit : Agave in “Botany of Bihar and Orissa”:
Unlike the “Bengal Plants”, “Botany of Bihar and Orissa” features 5 Agave spp., and provides KEY –

I. Leavers over 3 ft. in length, in lax rosette or tufted :-
    A. Perianth segments not constricted towards the tip :-
            1. L. broadest in the middle, tapering to both extremities :-
                     L. oblong-lanceolate, neck sharply constricted ………. americana L. (common ornamental plant throughout the province)
                     L. linear-oblong, neck not constricted …………….. vera-cruz Miller. (more or less naturalized in Singbhum etc)
            2L. linear-lanceolate, hardly widened in the middle ……… cantula Roxb.  (cultivated)
    B. Perianth segments narrowed from about the middle to a ligulate tip :-
                 L. straight and narrow, often spineless …………. sisalana Perrine (introduced into Tirhut etc)

II. Leaves never exceeding 3 ft., in a close globose rosette …….. wightii Dr. & Prain (Tirhut)


I don’t know why the KEW page of Agave vera-cruz doesn’t open now.

This came to my notice that many many of the reference pages I linked in various discussion threads are either removed or moved to somewhere else.

However, GBIF page is still there – https://www.gbif.org/species/2766994 and a screenshot.



POWO page now opening.


Agave americana
L.
vera-
cruz
Mill.
cantula
Roxb.
sisalana
Perrine
wightii
Dr &
Prain
accepted name vivipara L. angusti folia
var.
angusti folia
leaves very stout, commonly variegated, very swollen base, sharply constricted neck above the base often rather concave just above the middle (widest part), leaf base thick, early curving upwards and ends more or less recurved moderate ly thick base, curving gradually outwards, or in weak specimen bent over almost from base not at all constricted above moderate ly thick base, base thin, broadly amplexi caule,
leaves (feature & orienta tion ) lanceolate, many in lax rosette, spreading at base, then ascending and finally tips often recurved; 4-6 ft log and upto 1 ft broad above the middle, margin distinctly sinuate and bearing reflexed spines (prickles) linear-oblong, 4-6 ft X upto 10 inch. linear-lanceolate, lax but even tuft, 4 ft or more, ut usually 2.25 inch broad; over 3 inch above the middle (widest part) not forming rosette, but closely tufted, inner leaves at sharp angle with the axis, outer less than a right angle; upto 6ft X 10 inch ensiform linear-lanceo late, vary many, forming a stiff even rosette; 3-5 ft X 2.5 inch, flat or very slightly convex
leaves (colour) some times rather glaucous very deep green, sage green, glaucous pale green, older darker, some times glaucous deep green, glaucous or not pale green often tinged with ashy gray
apical spine 1-2 inch long 0.5-1 inch dark brown usually acicular, 0.5-1 inch reddish or dark brown glossy, purple or dark brown 0.5 inch, pale. slightly decurrent
marginal prickles strong, dark brown spreading or decurved, black or dark coloured conspi cuous, falcate pointing forwards. .25 inch or more, very sharp absent or if present weak scattered and pale rather weak
scape 15-25 ft 12-18 ft 15 ft or more 12-15 ft
inflore scence primary branches almost horizontal main branches of panicle 3-choto mous, curved or flattened inflore scence on flexuous rather slender branches fascicles of flowers rather crowded main branches short 3-choto mous
tepals ovate lanceolate, tips obtuse linear-lanceo late, ovary smooth cylindric longer than perianth bluntly linear-lanceo late, or linear-oblong, otuse base of perianth convex and somewhat dialated, limb suddenly contract ed, segments narrowly ligulate, tip slightly hooded, Style long perianth cup soon dividing into lanceo late segments, each ending in a narrowly ovate lanceo late limb, slightly thickened at the obtuse tip


This is copybook image of Agave angustifolia prickles- Plantatlas no. 2 of Florida
Finally, I think, Sir, we should follow the  ” lucidcentral” KEY (which you have often referred to, in other threads of Agave, for the identification of the five apparently confusing species :- leaf margin with …..

  1. stout and conspicuous prickles = americanavera-cruz and cantula (vivipara)
  2. prickles relatively weak, but present and with special character (screenshot Haines_03) = angustifolia
  3. prickles absent or if present weak, not dark coloured, straight, intermittent or not = sisalana
Because, I have searched and noted many many GBIF and KEW herbarium, I have decided :-
  1. flowers are not reliable identifier (because close up of live flower photograph of all the species are not available)
  2. leaf orientation or angle of attachment to the stem (rosette or not) is not very reliable, because all type can be seen in all species
So, I think, as you always stated, that the margin prickles the first level of determiner,  thereafter the KEY and the TABLE in this thread.
I attach herewith pages from Haines’ book and protologue of Agave vera-cruz.

5 attachments


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Agave angustifolia Haw. (Images by J.M.Garg, Aarti S Khale (Validation by Ajinkya Gadave) & P Santhan (Inserted by J.M.Garg) (For moe photos & complete details, click on the links))

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Agave attenuata Salm-Dyck (Images by Satish Phadke (Validation by Ushadi & J.M.Garg),  Ranjini Kamath & Bindu (Identified by Neil Soares) (Inserted by J.M.Garg))

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Agave x leopoldii (Images by Satish Phadke’s friend (Id by Tanay Bose) (Inserted by J.M.Garg) (For more photos & complete details, click on the links))

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Agave potatorum Zucc. (Images by Balkar Singh & Aarti S Khale (Id by Tanay Bose) (Inserted by J.M.Garg) (For more photos & complete details, click on the links))

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Agave victoriae-reginae T.Moore (Images by Aarti S Khale (Id by Ajinkya Gadave), Alka Khare (Validation by Ushadi) & Balkar Singh (Inserted by J.M.Garg) (For more photos & complete details, click on the links))

 

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Agave vivipara L. (Aruba, Bonaire, Curaçao; Introduced into: Bangladesh, Canary Is., India, Nepal, Pakistan as per POWO)

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Furcraea foetida (L.) Haw. (Images by tspkumar (Id by Kotaimuthu & Vijayasankar Raman) & Bhagyashri Ranade (Id by Gurcharan Singh) & Prashant Awale (Id by Nayan Singh) (Inserted by TSP Kumar & J.M.Garg) (For more images & complete details, click on the links))

/wp-content/uploads/2020/10/1-Magadi%2520handpost-ckm-20141104_161707%2520-21-.jpg/wp-content/uploads/2020/10/6-Magadi%2520hand%2520post_ckm_20150305_153147%2520-29-.jpg/wp-content/uploads/2020/10/2-Magadi%2520handpost-ckm-20141104_161707%2520-6-.jpg/wp-content/uploads/2020/10/290920112141.jpg

Furcraea selloa K.Koch (Images by Ranjini Kamath (Id by J.M.Garg) (Inserted by J.M.Garg) (For more images & complete details, click on the links)) 

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From Floral Database of Tamilnadu :

Binomial Habit Notes Ref. Distrib.
Agave
americana
L.
Shrub Plains to High
Altitudes, Cultivated, Native of Tropical America
Flora of Tamil
Nadu, VOL. III, 1989
All districts
Agave angustifolia Haw. Herb Plains
to High Altitudes, Cultivated, Native of Tropical America
Flora
of Tamil Nadu, VOL. III, 1989
All
districts
Agave sisalana Perrine ex Engelm Shrub Plains
to High Altitudes, Cultivated, Native of Tropical America
Flora
of Tamil Nadu, VOL. III, 1989
All
districts
Agave vera-cruz Mill. Shrub Plains
to High Altitudes, Cultivated, Native of Tropical America
Flora
of Tamil Nadu, VOL. III, 1989
All
districts

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Botanical name Synonyms Family Common name
Agave americana Agavaceae Century Plant
Agave angustifolia Agave wrightii Agavaceae Caribbean Century Plant
Agave attenuata Agavaceae Swan’s Neck Agave
Agave sisalana Agave rigida var. sisalana Agavaceae Sisal Agave

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Gardening in India By George Marshall Woodrow, G Marshall (1999)- Brief details-

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Flora of Davanagere District, Karnataka, India By B. K. Manjunatha, V. Krishna, T. Pullaiah  (2004)- Details-
Agave americana


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Agave : 1 post by 1 author.

I have updated eFI(efloraofindia) page on Agave

Attempts have been made to incorporate most of the species available in India & nearby areas with details & keys directly or through links as far as possible. It’s quite possible that there may be some discrepancy in the accepted names & synonyms taken from other links.

Species discussed so far in efloraofindia are given at the bottom of the page in the form of links against Subpages. On clicking them one can see all the details.

If someone can provide complete list of Indian species with source references it will be wonderful.

Any comments/ corrections are welcome.


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Pl. go through‎ Agave (‎‎‎‎‎‎Asparagaceae) page with images of species (done by me & …) in efloraofindia.

If you find any mis-identification, pl. let us know. If anybody can send images of other species of this genera (for incorporation in the website), if any, it will be really nice.
Also, if anybody is interested to take up the activity of inserting images on efloraofindia pages from efloraofindia posts, pl. let us know.


looks good


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