Very good; you have very good observation skills! Yes, the new growth
of the Ludwigia is definitely 'hooking downward at the leaf tip
" The older leaves
of the Bacopa are indeed 'rolling' or 'curling' at the leaf margins
(btw doesn't really matter if the curl is upward or downward - seems to be species related).
Depending upon the severity of the deficiency, and the species, plants may show one, two, or several of these characteristics:
Symptoms appearing first or most severely on new growth (root and shoot tips, new leaves)
A. Terminal bud usually dies. Symptoms on new growth.
2. Necrosis occurs at tip and margin of leaves causing a definite hook at leaf tip.
Calcium is essential for the growth of shoot and root tips (meristems). Growing point dies. Margins of young leaves are scalloped and abnormally green and, due to inhibition of cell wall formation, the leaf tips may be "gelatinous" and stuck together inhibiting leaf unfolding. Stem structure is weak and peduncle collapse or shoot topple may occur. Roots are stunted. Downward curl of leaf tips (hooking) occurs near terminal bud. ammonium or magnesium excess may induce a calcium deficiency in plants... calcium deficiency
Differentiating between calcium and boron deficiency symptoms: When calcium is deficient, there is a characteristic hooking of the youngest leaf tips. However, when boron is deficient, the breakdown occurs at the bases of the youngest leaves. Death of the terminal growing points is the final result in both cases
Symptoms do not appear first or most severely on youngest leaves: Effect general on whole plant or localized on older, lower leaves.
C. Interveinal chlorosis. Interveinal chlorosis first appears on oldest leaves.
1. Older leaves chlorotic, usually necrotic in late stages. Chlorosis along leaf margins extending between veins produces a "Christmas tree" pattern. Veins normal green. Leaf margins may curl downward or upward with puckering effect. Necrosis may suddenly occur between veins. Potassium or calcium excess can inhibit uptake of magnesium...magnesium deficiency
When the external magnesium supply is deficient, interveinal chlorosis of the older leaves is the first symptom because as the magnesium of the chlorophyll is remobilized, the mesophyll cells next to the vascular bundles retain chlorophyll for longer periods than do the parenchyma cells between them. Leaves lose green color at tips and between veins followed by chlorosis or development of brilliant colors, starting with lower leaves and proceeding upwards. The chlorosis/brilliant colors (unmasking of other leaf pigments due to the lack of chlorophyll) may start at the leaf margins or tips and progress inward interveinally producing a "Christmas" tree pattern. Leaves are abnormally thin, plants are brittle and branches have a tendency to curve upward. Twigs are weak, subject to fungus infection, usually leaves drop prematurely; plant may die the following spring.
Now it appears you have both problems, is that possible? Certainly, some plants require more calcium than others and some plants require more magnesium than others. I grew up in St. Louis (Webster) and my wife's relatives still live in the area....what has happened the last few months that may have effected your water supply.....flooding! It is possible that all that snowmelt, and rain runoff has diluted the 'normal' amount of Ca and Mg in your water causing these issues. Tested your tap water lately?
Bet you can guess the next question, what course of action would you suggest?