Affinis

Affinis (Species affinis) [ Taxonomy ]	Dictionary of botanic terminology - index of names
Abbreviation: Aff. (sp. aff.) - affin.

Related to but not identical with the named taxon; usually applied to a taxon believed to be undescribed;

The term affinis (or sp. aff = species affinis) is used when the identity of a distinct biological species is unknown but it has a striking similarity or close relation with a known species. (eg: Trichocaulon aff. flavum, means a distinct species of Trichocaulon which is similar or has affinity with T. flavum but is NOT T. flavum, but a related species not exactly identical to it. An undescribed taxon that further taxonomic study will decide to confirm if it is the same or not.

Alternative use of the term "sp. aff. or affin." and “cf.” in taxonomy:

"sp. aff. or affin." (Latin for affinis = related to) as used in scientific papers, indicates that the specimen is closely related to the named species but show features that make it obvious that it is a different species.
"cf." (Latin for confer = compares with) is used in similar papers to indicate that the specimen resembles the named species very closely, but has certain minor features not found on the type specimens. Whether it is a different population of the named species or a different species altogether would require more research into the species' population variations than was undertaken by the author.

In practical terms the author decides whether to use "cf." or "sp. aff." based on his own experience

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Holdfast roots [ Botany ]
Dictionary of botanic terminology - index of names

Some species of climbing plants develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place.

Climbing plants, like the poison ivy (Toxicodendron radicans), Boston ivy (Parthenocissus tricuspidata), and trumpet creeper (Campsis radicans), develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place. Usually the Holdfast roots die at the end of the first season, but in some species they are perennial. In the tropics some of the large climbing plants have hold-fast roots by which they attach themselves, and long, cord-like roots that extend downward through the air and may lengthen and branch for several years until they strike the soil and become absorbent roots.

Major references and further lectures:
1) E. N. Transeau “General Botany” Discovery Publishing House, 1994