I have found what may be the holy grail. It is a book known as "A Botanical Materia Medica" by Jonathan Stokes. This has several volumes, but the one you want is volume 1, which has no appended "volume X" in the title.
A list of abbreviations can be found on page XIII (or 13 for those not familiar with Latin numerals), just after the ...
Great Basin bristlecone pines (Pinus longaeva) have been known to live to be thousands of years old.
The oldest known living individual is named Methuselah and is estimated to be more than 4,800 years old. It's been credited as the oldest living non-clonal organism on Earth.
There are multiple other trees over 1000s years old.
Yes there are many aquatic plant species which do not stand up in water.
You need to look at the lifeform of the plants, such as introduced by Raunkiaer ( https://en.wikipedia.org/wiki/Raunki%C3%A6r_plant_life-form ) and later work by Ellenberg & Mueller-Dombois (1967).
In fact, you're mixing up two different lifeforms :
true aquatic plants are unable ...
There are a variety of methods for visualizing elements in plants. Here is a review discussing various such methods.
As suggested by other answers, radioisotopes are one such means (works in vivo?).
One may also use X-ray spectroscopy: "With x-ray fluorescence-based approaches, elements are detected based upon their characteristic fluorescent x-rays. ...