this thread is almost a year old but there still morons that wanna argue
"marijuana, the sap is usually colourless, although a bright redcolour - it lookslike blood - is not uncommon in later life. The red colour is due to haematin compounds and anthocyanin pigments that naturally build up in some varieties. The red colour may also indicate a nutrient deficiency, notably of nitrogen, phosphorus, potassium, or magnesium." (posted by my boi Luda)