The pre-human plant (prior to cultivation manipulation) is a modest herb that finds its comfort on rocky outcroppings of limestone, local to north Mediterranean sea coasts. It is a two year plant (biennial) that stores it’s energy into it’s leaves the first year so to burst, with reproductive fervor, in it’s second, and final, year. This glory is manifested as a spike of a yellow, four-petaled flowers. Whether or not these lovely cross-like (crucifix) flowers are pollinated or not, the plant diminishes back to mother earth. But the rest of this plant’s potential requires you to read on.
“Oleracea” means “potherb” or “cabbage” in vague Latin parlance. Etymologically, the name is based on the fact that the aforementioned modest weed was lush with it’s “head” and so good for stews in the “pot”. Regardless, we should marvel in the variety innate to this lovely plant:
One species, many forms: Kale, broccoli, cauliflower, cabbage, kohlrabi, Brussels sprouts, Chinese broccoli, and collard greens. These are all technically the same species (i.e. inter–fertile), but with diverging cultivar lineages which can be understood as subspecies. In produce or manufacturing contexts, no reproductive parts are modified, leaving the flowers and fruit/seeds indistinguishable between the cultivars. This is so food product is maximized and reproduction minimized. In other words, this plant is best for it’s flesh and fiber and worthless for it’s fruit and flower.
The tight, bumpy white “curd” forming a cauliflower head results from extensive proliferation of many mutant inflorescence meristems on top of the initial inflorescence branches that become arrested at the inflorescence meristem stage. They never elongate into more inflorescence or produce floral meristem. If cauliflower is left to develop instead of being picked when the curd is at its most dense, as is preferable in the kitchen, the curd would loosen and about 10% of the inflorescence meristem would go on to produce floral meristem and finally flowers, which is why we have cauliflower seeds at all. Broccoli shares inflorescence meristem proliferation followed by arrested inflorescence development with cauliflower, although broccoli’s inflorescence meristems do go on to produce floral meristem and initiate floral development before further expansion of the inflorescence ceases.
Collectively the many species in the Brassicacea family produce over 120 different glucosinolates, and the hydrolysis products of some of them are the pungent, sharply spicy mustard oils characteristic of the family. When the plant is assaulted, there are specified cells holding glucosinolate and some break, releasing the glucosinolates, which mix with enzymes (myrosinases) that change them to defense compounds. Enzymes in herbivore guts can also accidently do this reaction, making them ill after ingesting the taste herb. Every organ in cruciferous plants—leaves, roots, flowers, fruit, seeds—has the glucosinolate-myrosinase defense system.
If you want to grow cruciferous vegetables ensure that your soil has adequate levels of sulfate. Crucifers have what you might call a high-sulfur lifestyle. Glucosinolates are rich in sulfur, as are several other important abundant compounds in crucifers, including amino acids cysteine and methionine, antioxidant glutathione, and phytoalexin S-methyl cysteine sulfoxide (defensive chemical). Notably, SMCSO is degraded during cooking as thermal energy breakes the molecules’ complex bonds, making your house smell and your food less nutritious. Culinary tip: sweat or lightly steam/fry; never over cook your B. oleraceae or you’ll lose out on the nutrients.
Glucosinolates are derived from different amino acids, forming three broad classes: indolic, aliphatic, and aromatic glucosinolates. Each class seems to have a different induced reponse to herbivory. Glucoraphanin is an aliphatic glucosinolate, derived from amino acid methionine. Herbivory induces the strongest increase in indolic glucosinolates, from 1.2- to 20-fold. Aliphatic and aromatic glucosinolate concentration regularly increases 1.2- to 3-fold in response to herbivory, but sometimes their concentration actually declines. In people, the hydrolysis products, especially isothiocyanates, contribute to demonstrable cardiovascular and cancer risk reduction benefits of a diet high in crucifers. High crucifer consumption is also linked with hypothyroidism and anemia, albeit circumstantially.