Easily confused with :
Garden Lupin (Lupinus polyphyllus) [indeed, Russell Lupin is a hybrid between that and Tree Lupin (Lupinus arboreus)]. It is also often recorded as Garden Lupin even though gardeners hardly ever plant Garden Lupin nowadays preferring varieties of Russell Lupin instead, so if any escape, it is usually a Russel Lupin rather than Garden Lupin.
Is the Hybrid of :
Garden Lupin (Lupinus polyphyllus) and Tree Lupin (Lupinus arboreus).
Hybridizes with :
Nootka Lupin (Lupinus nootkatensis) to produce the triple hybrid Lupinus × regalis × nootkatensis which has no common name and hasn't been seen in a single hectad in the UK since 1986 and before that was only ever seen in one single hectad near Poole.
Some similarities to :
Nootka Lupin (Lupinus nootkatensis) which is shorter at only 1m, has fewer leaflets (6-9) [but can have up to 12] and has long shaggy hairs growing on high moors or on river shingle mainly in Scotland.
Like all Lupins, Russell Lupin is poisonous, the seeds especially so. They contain Lupanine, Sparteine and other poisonous bis-quinolizidine alkaloids which cause salivation, vomiting, problems with swallowing, hyperthermia, cardiac arrhythmia, mydriasis (dilation of pupils), excitement, delirium and finally paralysis. Death is through respiratory arrest, but there are treatments for Cytisine poisoning before that happens. Lupins also contain the poisonous quinolizidine alkaloid Lupinine (not to be semantically confused with Lupanine, which is a bis-quinolizidine alkaloid).
Worldwide there are about 280 differing species of wild Lupin.
Those folk with an allergy to Peanuts should avoid handling Lupins because that may also cause an allergic reaction.
ABSCISIC ACID (ABA) - a ubiquitous hormone
Abscisic Acid is an ubiquitous and multi-functional plant hormone discovered in 1961 to 1963 in Cotton plants and Lupin by several researchers. It has since been found to be vital for the growth of most (if not all?) plants. It is a stereoisomeric molecule which can exist in two forms, the (S)-cis-Abscisic Acid and (R)-cis Abscisic Acid forms, of which only the former exhibits hormonal activity in plants.
Since Cotton is non-native to the UK, your Author has put it under Lupin, but it occurs in most (all?) plants. It was names Abscisic Acid because it was first thought to be only involved with abscission in plants (the shedding of parts of a plant, such as seeds, leaves, fruit, flower etc) but it is now known to be involved in a great many other ways in which plants grow and senesce. ABA is also produced by some plant pathogenic fungi for nefarious reasons.
It is now known that Abscisic Acid promotes seed dormancy, assists tolerance to desiccation, and inhibits precocious germination during seed development. It also enhances root growth unless they are stressed by shortage of water in which case it inhibits root growth. It also boosts closure of the stomata to help preserve internal water and accelerates leaf senescence.
ABA is located everywhere in the plant; but concentrations of it vary from 1 to 15nM in the xylem, or up to 3000nM within water-stressed leaves.
Abscisic Acid is synthesized within plants from Zeaxanthin via trans-
Violaxanthene to produce first
Xanthoxin which is eventually transformed into Abscisic Acid.
Abscisic Acid is 'in-activated' by being transformed into either Phaseic Acid (itself a hormone found in plants) or to its -β-D-Glucose-Ester. But Phaseic Acid is also a plant hormone which is associated with arresting of photosynthesis and abscission (the shedding of parts of a plant, such as seeds, leaves, fruit, flower etc). High levels of Phaseic Acid impede the closure of stomata (the opposite effect to Abscisic Acid) and to reduce photosynthesis (at least in Thale Cress). Therefore the two hormones Abscisic Acid and its decomposition product Phaseic Acid act partly in opposition to each other, providing a finer level of control that is possible from differential systems, such as in the Ascorbic Acid/Gibberellic Acid (which are both hormones) differential ratio as described on the Danish Scurvygrass page.
See the Violaxanthin Cycle where the balance of Violaxanthin, Antheraxanthin and Zeaxanthin helps protect plants from excess sunlight, which is another balanced cycle.