Aspects of the natural history of Lycium
(writing in progress)
Lycium (https://www.inaturalist.org/observations?taxon_id=58333), which belongs to the tomato family (Solanaceae, https://en.wikipedia.org/wiki/Solanaceae), is an interesting genus biogeographically.
Lyciums occur on all vegetated continents (https://en.wikipedia.org/wiki/Lycium#/media/File:Carte_lycium.jpg), but the Americas are particularly important.
There are many species in both North and South America, and if there is a real centre for the genus in terms of sheer number of species, it is southern South America, e.g. La Pampa (https://en.wikipedia.org/wiki/La_Pampa_Province), Patagonia (https://en.wikipedia.org/wiki/Patagonia), and perhaps the Monte (https://en.wikipedia.org/wiki/Monte_Desert) and the Chaco (https://en.wikipedia.org/wiki/Gran_Chaco).
South America also has the greatest adaptive diversity within the genus.
For example, the South American species include some with the typical orange berries and others with odd, two-seeded, non-succulent fruits of unknown dispersal mechanism. The genus thus conforms to the concept of 'plasticfruits' (see my Posts of...).
Even in North America, lyciums are remarkably widespread in the various dry biomes of the southwestern USA and Mexico, including coastal sage (https://en.wikipedia.org/wiki/Coastal_sage_scrub), sonoran (https://en.wikipedia.org/wiki/Sonoran_Desert) and mojave (https://en.wikipedia.org/wiki/Mojave_Desert) deserts, pinyon-juniper woodland (https://en.wikipedia.org/wiki/Pinyon%E2%80%93juniper_woodland), etc., as well as reaching to e.g. Florida.
Eurasia too has plenty of lyciums (indeed, the name Lycium itself hails from Anatolia). It is from a Chinese species that the well-known goji berries of health food shops hail (https://en.wikipedia.org/wiki/Goji). This species is broad-leafed, and not as xerophytic (https://en.wikipedia.org/wiki/Xerophyte) as most of the species of semi-arid Africa, North America, and South America.
Lycium reaches Australia. Here it is widespread, but in the form of only one indigenous species. So, Australia is the odd continent out in the sense that lyciums are minimally poorly differentiated here, and possibly a relatively recent arrival.
The flower form in this genus varies enough that some species are pollinated by hummingbirds, others by insects.
The fleshy fruits are eaten by both the North American phainopepla and the Australian mistletoebird (https://en.wikipedia.org/wiki/Mistletoebird), both of which are known mainly for their role in dispersing and sowing mistletoes (https://en.wikipedia.org/wiki/Mistletoe). So, there is a functional link between lyciums and mistletoes, despite the general lack of phylogenetic or ecological affinity in other respects. It would be interesting to study those lyciums prone to infestation by mistletoe.
The fleshy fruits of lyciums are generally edible to humans, at least in limited quantities. However, as is not surprising for the Solanaceae, there is some tendency towards toxicity. The fruits of some species may be toxic when unripe and at least one species has fruits which are toxic even when ripe.
The rodent Psammomys seems to eat the foliage of lyciums in North Africa, perhaps in parallel with Parotomys or other Otomys-related rodents in southern Africa. American packrats (Neotoma) are also associated with lyciums although I’m not sure if they eat the leaves. I get the impression that such herbivory as takes place on lycium foliage is more among monogastric animals (including equids and colies) than among ruminants. Lyciums play an ‘interstitial’ role, if you like, in landscapes dominated by ruminants and their forage plants.
All lyciums seem to have a large ratio of root to above-ground biomass, with extensive roots spreading up to 9 m from the base of the plant despite the modest size of the shrubs. All species also seem to be deciduous, in most cases drought-deciduous. Lyciums seem to have potential as ‘living fences’ i.e. spinescent hedges. I get the impression that some American species can form thickets, extensive enough to surprise South African botanists who are used to seeing lyciums only as scattered plants in the Karoo and Highveld, and who are used to discounting lyciums when it comes to the composition of our main thicket vegetation types such as spekboomveld.
In general, lyciums occur in environments free from fire. They are also generally eutrophic with a tolerance for base-rich and even saline soils. However, most species would not be called halophytes.
Biogeography of genus Lycium: http://www.weeds.org.au/WoNS/africanboxthorn/docs/Feasibility_of_biological_control_of_boxthorn_final.pdf
It is interesting that hummingbirds pollinate american lyciums: http://www.fs.fed.us/database/feis/plants/shrub/lycand/all.html.
Reading that the cultivated Chinese species Lycium barbarum lives only to a maximum of eight years, I was curious about the longevity of wild spp. of Lycium, which give the impression of being durable, gnarled, and long-lived in their semi-arid habitats.
The references excerpted below state that the wild spp. of Lycium in the semi-arid southwest of North America are quite long-lived, up to 90 years. So the cultivated Chinese species has either been selectively bred to be short-lived, or represents an ancestral species that is shorter-lived than more ‘typical’ congeners.
It’s also interesting to note that Lycium has shallow, wide-spreading roots, NOT deep roots. Deep roots in the Mojave Desert are associated with evergreens, and Lycium is drought-deciduous, using its wide-spreading roots not for evergreenness but for persistence through droughts in a dormant state.
I suspect that the various southern African spp. of Lycium (which are indeed drought-deciduous) are like their Mojave and Sonoran congeners: long-lived, shallow-rooted but with roots spreading up to 9 m from the base of the plant within 0.5 m of the ground surface.
http://www.fs.fed.us/database/feis/plants/shrub/lycber/all.html
Lycium barbarum of Eurasia does not necessarily have succulent leaves: http://en.wikipedia.org/wiki/Lycium_barbarum#mediaviewer/File:Lycium_barbarum_Flower_Closeup_Miguelturra_CampodeCalatrava.jpg
Leaves of lycium chinense hardly look succulent: http://en.wikipedia.org/wiki/Lycium_chinense#mediaviewer/File:Lycium_chinense_2.JPG
Another non-succulent lycium, this one from South America: http://photography-fotografias.blogspot.com.au/2012/08/fotos-frutos-photos-fruits-plants.html
Confirming that lycium australe of Australia is succulent:
http://florabase.dpaw.wa.gov.au/browse/profile/6967
Therenis a hint that the mountain zebra may have eaten lycium.
Although zebras are mainly grazers, they have some interesting habits when it comes to supplementary browsing. The following hints that Lycium may be among the plants browsed by equids on occasion. This is interesting because Lycium is strongly defended with stem spines for a plant that seems rather unattractive to most ruminants such as eland. I’ve long pondered the niche of lyciums w.r.t. herbivory, finding them rather incongruous. This the first indication that monogastrics may find this plant more palatable than ruminants do, and I speculate that the desert warthog may have dug up the roots of Lycium, which are extensive (they can reach up to 8m from the plant despite the modest size of the shrub, at least in the American spp.).
http://www.fs.fed.us/database/feis/plants/shrub/lycand/all.html
(writing in progress)
Usá ArgentiNat con app iNaturalist
Comentarios
Agregar un comentario