Order 7. =Nyctaginiaceæ.= The characteristic feature of this order is the _single_, regular, _united_, and often petaloid perianth, the lower part of which generally persists after flowering and embraces the fruit as a false pericarp. The upper portion is most frequently _valvate and folded_, or simply valvate in æstivation. The number of stamens varies. The free gynœceum is _unicarpellate_ and has 1 ovule. The fruit is a _nut_, but becomes a _false drupe_, since the lower persistent portion of the perianth becomes fleshy (as in _Neea_, where this fleshy part is almost always crowned by the upper persistent part of the perianth. In the majority of the Mirabileæ the lower part becomes the dry _anthocarp_, while the upper petaloid part falls away after flowering). Finally, a peculiar involucre is formed around the flowers by free or united floral-leaves.--The majority are herbs, some are trees (_Pisonia_, etc.); _Bougainvillea_ is a liane. The stems are often nodose and swollen at the nodes; the leaves are simple, penninerved, scattered, or opposite, without stipules. ~In some, the vascular bundles are scattered; stem anomalous.~ _Mirabilis_; the structure of the stem is abnormal. Dichasial branching with continuation from the second bracteole, thus forming unipared scorpioid cymes. The perianth is petaloid, funnel-shaped, and has a folded and twisted æstivation resembling that of the corolla of the _Convolvulaceæ_; the upper coloured portion falls off after the flowering. Outside, and alternating with it, is a 5-partite, sepaloid involucre of 5 spirally-placed floral-leaves.--_Oxybaphus_; the involucre envelops 1–3 dichasial flowers.--_Bougainvillea_; the involucre is rose-coloured, 3-leaved, and envelops 3 flowers (placed laterally; the terminal flower wanting). The leaves of the involucre in _Boerhaavia_, _Pisonia_, _Neea_, and others are reduced to teeth or scales. 157 species; mostly in tropical countries, and especially S. Am. Species of _Mirabilis_ (Am.) are ornamental plants. Theïn is found in _Neea theïfera_ Oersted (discovered by Lund in Lagoa Santa, Brazil), which may be used as a tea-plant. Order 8. =Aizoaceæ.= Only 3 _whorls_ are found in the flower, which _alternate_ with one another when their leaves are equal in number. The first is sepaloid, the third one the carpels, and the intervening one is either uncleft, in which case it is developed as stamens, or it is divided into a large number of members which then all become stamens (arranged in groups), or the outermost ones become developed as petals. The fruit is most frequently a capsule with several loculi. Most of the species are herbs with thick, fleshy stems, and exstipulate leaves. The structure of the stem is usually anomalous.