The difference between stems, stalks, and petioles in rhubarb

This is the wonderful rhubarb season!  And for those of us that like the tart flavor, the red shiny stalks (or sometimes green) makes us imagine pies, fruit tarts, jams, and sauces...   Rhubarb is also showing up in spring issues of cooking magazines, radio shows, newspaper articles, and so on.

The inaccuracy that often is perpetuated with rhubarb is what we properly call the name the plant part we eat.  The 'stalks' we eat is the edible part of the otherwise toxic plant, and it is the leaf stalks.  The botanical, scientific name for this in English is 'petiole'.  This photo shows clearly how each stalk is connected to each leaf.

Rhubarb leaves with edible leaf stalks/petioles.
(cc) Dieter Weber, Wikipedia

The problem is that many times people inaccurately call it rhubarb stems.  A stem is a part of the plant that is a central shoot that holds the leaves, branches, flowers, and so on.  The true rhubarb stem is a hollow, nearly bamboo-like cylinder, which leads up to a terminal shoot that eventually develops flower buds. A stalk, on the other hand, can be both leaf stalk and the stem of a plant. Here is a photo of a rhubarb stem with flowers and small leaves:

Flowering rhubarb stem.
(cc) Septuagent on Flickr

Here are some examples of botanical inaccuracy when it comes to written online rhubarb information :

Wikipedia: "The use of rhubarb stems as food is a relatively recent innovation, first recorded in 17th century." 
{But Wikipedia gets it right in the beginning of the article on rhubarb.}

Royal Horticultural Society (RHS): "Rhubarb is a rhizomatous perennial whose stems (‘sticks’) grown as vegetable but used mainly as a dessert."   "Stems should be pulled rather than cut to prevent rotting of the remaining stump. "

Mark Bittman for The New York Times: "Buy the smallest stems you can find and use a vegetable peeler or paring knife to remove the stringy outer layer."